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feat: Deferred (proxied) tools can now be composed via the Bash tool - #360

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feat/deferred-tools
Aug 18, 2026
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feat: Deferred (proxied) tools can now be composed via the Bash tool #360
jcarver989 merged 29 commits into
mainfrom
feat/deferred-tools

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@jcarver989 jcarver989 commented Aug 18, 2026 •
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Summary

Aether has long supported a "proxy" for tools that allowed progressive discovery by deferring when we load MCP tools into context. Prior to this PR we would do this by writing proxied tools to a tmp dir on the file system, which allowed the agent to use its Bash tool to dynamically discover and load tool schemas.

This worked very well, but one major downside is the agent was unable to compose tool calls in a way that avoided tool results passing directly into context.

CloudFlare's Code Mode was an early experiment to sidestep this problem by giving the agent a tool to write TypeScript that called MCP servers.

Changes

This PR gives Aether the equivalent of a "code mode". But, instead of embedding an interpreter for TS, Lua or Bash, we allow the agent to compose MCP tool calls using its Bash tool by giving the our CLI a mcp sub-command to list servers, their tools, and call a tool. This allows the agent to compose tool calls via Unix pipes, pipe tool results into jq, pipe output to files and...all sorts of other useful things.

@jcarver989
refactor(mcp-utils): Extract ToolFilter into mcp-utils
3455ad1
@jcarver989
refactor(mcp-utils): Extract ToolCatalog
7d68a63
@jcarver989
refactor(mcp-utils): Hookup new ToolFilter and ToolCatlog to manager.rs
849bca8
@jcarver989
chore: Update other crates to use ToolCatalog and ToolFitler
cba4670
@jcarver989
refactor(mcp-utils): Introduce InMemorySeverSpec and RuntimeMcpServer to
f2e7762 
prepare for lazy init of built in servers
@jcarver989
refactor(mcp-servers): Lazily init buitl in mcp servers
ac146ad
@jcarver989
refactor(aether-core): refactor mcp builder to construct built in
71f6ec5 
servers wihtin spawn()
@jcarver989
refactor(aether-cli): Updates based on upstream changets.
b0e4fd3
@jcarver989
chore: Update README code example
b3b0934
@jcarver989
refactor: Add McpSnapshot and McpHandle types to simplify implementin…
81ea71a 
…g tool deferral
@jcarver989
refactor: Synchronize tool refresh
1e07862
@jcarver989
feat(mcp-utils): Add UnixSocketMcpTransport
264eeb3
@jcarver989
chore(mcp-servers): Add aether exe to environment of Bash tool call s…
1a981fc 
…o aether can call itself
@jcarver989
feat(ather-core): Add GatewayService MCP server for deferred tools ov…
e4c331d 
…er a unix socket, to support aether being able to

compose MCP tool calls in Bash
@jcarver989
chore(mcp-servers): Wire Bash env into coding mcp
f4e9858
@jcarver989
chore(mcp-utils): tokio select to handle cancellation token in UnixSo…
659dbab 
…cketMcpTransport
@jcarver989
chore(mcp-utils): Wire in progressive discovery instructions in to ma…
feaa663 
…nager.rs
@jcarver989
chore(mcp-servers): Add progressive discovery instructions
3daa994
@jcarver989
chore(aether-core): Wire progressive discovery instruction into builder
c1a6782
@jcarver989
feat(aether-cli): Add mcp sub-command so aether agents can call mcp t…
a1fe5c2 
…ools via bash composition
@jcarver989
refactor(aether-settings): Rename proxy setting to deferTools for cla…
5c259ad 
…rity
@jcarver989
chore(aether-core): Rename proxy to deferred_tools for clarity
2b28e12
@jcarver989
chore(mcp-utils): Rename proxy to deferred_tools for clarity
06f6ba9
@jcarver989
chore(aether-cli): Rename proxy to deferred_tools for clarity and fix…
d0422af 
… issue with mcp sub-command
@jcarver989
chore(mcp-servers): Fix unreleased issue with using piped Stdio when …
171d223 
…we shouldn't
@jcarver989
chore(wisp): Rename proxy language to deferred tools for clarity
2f35cea
@jcarver989
chore(acp-utils): Rename proxy to deferred tools for clarity
4243936
@jcarver989
chore(website): Update docs
dbf1392
@jcarver989 jcarver989 changed the title refactor: Prepare for better deferred tools implementation. feat: Deferred (proxied) tools can now be composed via the Bash tool Aug 18, 2026
@jcarver989
jcarver989 marked this pull request as ready for review August 18, 2026 16:01
@jcarver989
jcarver989 merged commit 4eca62e into main Aug 18, 2026
13 checks passed
@jcarver989
jcarver989 deleted the feat/deferred-tools branch August 18, 2026 21:13
@contextbridge-pr-automation contextbridge-pr-automation Bot mentioned this pull request Aug 14, 2026
Merged
jcarver989 pushed a commit that referenced this pull request Aug 19, 2026
@contextbridge-pr-automation
chore: release (#326)
2024921 
## 🤖 New release

* `aether-auth`: 0.1.11 -> 0.1.12
* `aether-utils`: 0.2.11 -> 0.2.12
* `aether-llm-codegen`: 0.2.18 -> 0.2.19
* `aether-llm`: 0.7.26 -> 0.7.27
* `aether-mcp-utils`: 0.5.31 -> 0.5.32
* `aether-acp-utils`: 0.3.37 -> 0.3.38
* `aether-agent-core`: 0.6.31 -> 0.6.32
* `aether-lspd`: 0.1.31 -> 0.1.32
* `aether-project`: 0.5.32 -> 0.5.33
* `aether-telemetry`: 0.1.12 -> 0.1.13
* `aether-mcp-servers`: 0.4.38 -> 0.4.39
* `aether-tui`: 0.2.19 -> 0.2.20
* `aether-wisp`: 0.4.39 -> 0.4.40
* `aether-agent-cli`: 0.7.35 -> 0.7.36
* `aether-evals`: 0.2.24 -> 0.2.25
* `aether-schemas`: 0.1.19 -> 0.1.20

<details><summary><i><b>Changelog</b></i></summary><p>

## `aether-auth`

<blockquote>

##
[0.1.12](aether-auth-v0.1.11...aether-auth-v0.1.12)
- 2026-08-19

### Added

- *(mcp)* support Client ID Metadata Documents
([#348](#348))

### Other

- Refactor/credential storage
([#345](#345))
</blockquote>

## `aether-utils`

<blockquote>

##
[0.2.12](aether-utils-v0.2.11...aether-utils-v0.2.12)
- 2026-08-19

### Added

- Allow proxying tools within a MCP server
([#341](#341))
</blockquote>

## `aether-llm-codegen`

<blockquote>

##
[0.2.19](aether-llm-codegen-v0.2.18...aether-llm-codegen-v0.2.19)
- 2026-08-19

### Other

- scheduled code-cleanup
([#331](#331))
</blockquote>

## `aether-llm`

<blockquote>

##
[0.7.27](aether-llm-v0.7.26...aether-llm-v0.7.27)
- 2026-08-19

### Added

- *(mcp)* support Client ID Metadata Documents
([#348](#348))

### Other

- Update models
([#363](#363))
- Update models
([#359](#359))
- Update models
([#349](#349))
- Refactor/credential storage
([#345](#345))
- cleanup warnings
- Update models
([#336](#336))
</blockquote>

## `aether-mcp-utils`

<blockquote>

##
[0.5.32](aether-mcp-utils-v0.5.31...aether-mcp-utils-v0.5.32)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))
- *(mcp)* support Client ID Metadata Documents
([#348](#348))
- Allow proxying tools within a MCP server
([#341](#341))
- *(mcp-servers)* Bash and Sub-agents can now be run in foreground or
background by main agent
([#340](#340))
- Support MCP tasks
([#339](#339))

### Fixed

- *(mcp)* classify OAuth challenges accurately
([#347](#347))

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- remove nested Cargo lockfiles
([#352](#352))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
- Prefer connecting with new 7-28-2026 mcp protocol
([#332](#332))
</blockquote>

## `aether-acp-utils`

<blockquote>

##
[0.3.38](aether-acp-utils-v0.3.37...aether-acp-utils-v0.3.38)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
</blockquote>

## `aether-agent-core`

<blockquote>

##
[0.6.32](aether-agent-core-v0.6.31...aether-agent-core-v0.6.32)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))
- *(mcp)* support Client ID Metadata Documents
([#348](#348))
- Allow proxying tools within a MCP server
([#341](#341))
- *(mcp-servers)* Bash and Sub-agents can now be run in foreground or
background by main agent
([#340](#340))
- Support MCP tasks
([#339](#339))

### Fixed

- *(mcp)* classify OAuth challenges accurately
([#347](#347))

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- remove nested Cargo lockfiles
([#352](#352))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
- scheduled code-cleanup
([#329](#329))
</blockquote>

## `aether-lspd`

<blockquote>

##
[0.1.32](aether-lspd-v0.1.31...aether-lspd-v0.1.32)
- 2026-08-19

### Other

- scheduled code-cleanup
([#328](#328))
</blockquote>

## `aether-project`

<blockquote>

##
[0.5.33](aether-project-v0.5.32...aether-project-v0.5.33)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))

### Other

- scheduled code-cleanup
([#328](#328))
</blockquote>

## `aether-telemetry`

<blockquote>

##
[0.1.13](aether-telemetry-v0.1.12...aether-telemetry-v0.1.13)
- 2026-08-19

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
- scheduled code-cleanup
([#329](#329))
</blockquote>

## `aether-mcp-servers`

<blockquote>

##
[0.4.39](aether-mcp-servers-v0.4.38...aether-mcp-servers-v0.4.39)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))
- *(mcp-servers)* Bash and Sub-agents can now be run in foreground or
background by main agent
([#340](#340))
- Support MCP tasks
([#339](#339))

### Other

- scheduled code-cleanup
([#331](#331))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
- scheduled code-cleanup
([#328](#328))
- release ([#325](#325))
</blockquote>

## `aether-tui`

<blockquote>

##
[0.2.20](aether-tui-v0.2.19...aether-tui-v0.2.20)
- 2026-08-19

### Other

- scheduled code-cleanup
([#331](#331))
</blockquote>

## `aether-wisp`

<blockquote>

##
[0.4.40](aether-wisp-v0.4.39...aether-wisp-v0.4.40)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))
- Support MCP tasks
([#339](#339))

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
</blockquote>

## `aether-agent-cli`

<blockquote>

##
[0.7.36](aether-agent-cli-v0.7.35...aether-agent-cli-v0.7.36)
- 2026-08-19

### Added

- Deferred (proxied) tools can now be composed via the Bash tool
([#360](#360))
- Allow proxying tools within a MCP server
([#341](#341))
- *(mcp-servers)* Bash and Sub-agents can now be run in foreground or
background by main agent
([#340](#340))
- Support MCP tasks
([#339](#339))

### Other

- *(deps)* bump agent-client-protocol from 0.14.0 to 2.0.0
([#285](#285))
- Refactor/credential storage
([#345](#345))
- Upgrade to rmcp 3.1.1 and MCP tool calls now use multi round trip
requests (MRTR)
([#337](#337))
- scheduled code-cleanup
([#329](#329))
- release ([#325](#325))
</blockquote>

## `aether-evals`

<blockquote>

##
[0.2.25](aether-evals-v0.2.24...aether-evals-v0.2.25)
- 2026-08-19

### Other

- scheduled code-cleanup
([#329](#329))
</blockquote>

## `aether-schemas`

<blockquote>

##
[0.1.20](aether-schemas-v0.1.19...aether-schemas-v0.1.20)
- 2026-08-19

### Other

- update Cargo.lock dependencies
</blockquote>


</p></details>

---
This PR was generated with
[release-plz](https://github.com/release-plz/release-plz/).

Co-authored-by: contextbridge-pr-automation[bot] <259134118+contextbridge-pr-automation[bot]@users.noreply.github.com>
@contextbridge-pr-automation contextbridge-pr-automation Bot mentioned this pull request Aug 19, 2026
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