Capability MCP

MCP servers

An MCP server is declared in mcpServers (in plugin.json, or a .mcp.json). agentgear parses each into the components IR as one of three kinds — Stdio, Http { url }, Sse { url } — then each backend renders it into that tool's own config shape. stdio is the verified path on every backend; remote (http/sse) fidelity varies and is called out per tool below.

Of the 25 backends, 24 host MCP — every one except pi, which has no native MCP surface. claude and copilot-cli read the servers straight from the plugin tree (no translation); the other 22 translate.

stdio shapes

The rendered server body differs by tool. The families:

• {command, args, env} — the JSON mcpServers majority (gemini, augment, devin, kimi, droid, qwen-code, cline, omp, kiro, antigravity family, …).
• type:"stdio" prefixed — cursor, jetbrains-copilot, vscode-copilot.
• type:"local" with an array command (command:[cmd, ...args]) — opencode, kilo.
• [mcp_servers.<name>] inline table — codex (TOML).
• extensions.<name> block — goose (YAML, {name, type:stdio, cmd, args, envs, enabled, timeout}).

copilot-cli renders no MCP shape at all: its plugin engine reads .claude-plugin/plugin.json directly.

Remote (http/sse) fidelity

Remote servers render in each tool's own dialect. Some read the rendered {type, url, headers} shape as-is, some key transport off a different field, some would reject the shape and void the file — those transports are skipped rather than written wrong. "Faithful" means it lands in the tool's native form and dials.

harness	remote verdict
claude	native, no translation (Claude Code reads the tree itself)
copilot-cli	native, no translation (copilot's own plugin engine reads the tree itself)
amp	faithful. type is inert; the tool infers transport from url
antigravity	faithful: sse rendered as native {serverUrl}; http skipped (no landing)
antigravity-cli	faithful: sse rendered as native {serverUrl}; http skipped (no landing)
augment	faithful. byte-matches the tool's own writer
cline	faithful: rendered with cline's literal streamableHttp/sse transport values
codex	faithful. streamable-HTTP only; sse maps onto the same url
crush	faithful. both transports dial-proven
cursor	faithful. type genuinely picks the transport
devin	faithful: rendered with devin's native {url, transport} form
droid	faithful. type is the live discriminator
gemini	faithful. native {url, type, headers?}
goose	http faithful; sse skipped (goose runtime-refuses sse, so a dead extension is never written)
jetbrains-copilot	faithful: {type, url} (headers will nest under requestInit.headers once plugins carry them)
kilo	faithful. type mandatory, dial-proven
kimi	faithful: rendered with kimi's native {url, transport} form
kiro	unproven (login-walled). native {url, headers}, examples carry no type
omp	faithful. matches native exactly
openclaw	faithful, canonical: renders {url, headers, transport} directly, matching the tool's own post-doctor --fix shape. no churn
opencode	faithful. both transports collapse into remote
pi	skipped. core pi has no native MCP surface
qwen-code	faithful: rendered with qwen's key-presence form (http {httpUrl}, sse {url})
vscode-copilot	http faithful (byte-preserved); sse skipped (VS Code rewrites sse to http, so writing it would churn)
zed	http faithful (native {url, headers}); sse skipped (zed has a single remote transport)

Where each server lands

The file and the key path each backend writes, with the stdio body and the remote shape.

harness	file	key path	stdio shape	remote shape
claude	plugin tree .claude-plugin/plugin.json (or .mcp.json)	mcpServers	{command,args,env}, ${CLAUDE_PLUGIN_ROOT} expands	native, no translation
amp	settings.json (or .jsonc)	amp.mcpServers (literal flat-dotted key)	{command,args,env}	{type,url,headers}, type inert
antigravity	~/.gemini/config/mcp_config.json	mcpServers	{command,args,env}	{serverUrl} sse-only, http skipped
antigravity-cli	~/.gemini/config/mcp_config.json (user) · <root>/.agents/mcp_config.json (project)	mcpServers.<name>	{command,args,env}	{serverUrl} sse-only, http skipped
augment	~/.augment/settings.json	mcpServers.<name>	{command,args,env}, no type	{type,url,headers}
cline	~/.cline/data/settings/cline_mcp_settings.json	mcpServers (global only)	{command,args,env}	{type:"streamableHttp"|"sse",url,headers}
codex	config.toml	[mcp_servers.<name>]	{command,args,env} inline table	{url}, streamable-HTTP only
copilot-cli	native — copilot plugin install copies the tree verbatim	n/a	native, no translation	native, no translation
crush	crush.json	root mcp.<name>	{type:"stdio",command,args,env}	{type,url,headers}
cursor	mcp.json	mcpServers	{type:"stdio",command,args,env}	{type,url,headers}, type picks transport
devin	config.json	mcpServers	{command,args,env}	{url,transport}
droid	mcp.json	mcpServers.<name>	{command,args,env}	{type,url,headers}, type is the discriminator
gemini	settings.json	mcpServers.<name>	{command,args,env}	{type,url,headers}
goose	config.yaml	extensions.<name>	{name,type:stdio,cmd,args,envs,enabled,timeout}	http {name,type:streamable_http,uri,…}; sse skipped
jetbrains-copilot	mcp.json	servers	{type:"stdio",command,args,env}	{type,url} (no flat headers key yet)
kilo	kilo.json	root mcp.<name>	{type:"local",command:[cmd,...args],environment,enabled}	{type:"remote",url,headers,enabled}, type mandatory
kimi	~/.kimi-code/mcp.json	mcpServers	{command,args,env}	{url,transport}
kiro	settings/mcp.json	mcpServers	{command,args,env}	{type,url,headers} (unproven, login-walled)
omp	mcp.json	mcpServers	{command,args,env}	{type,url,headers}
openclaw	openclaw.json	mcp.servers.<name>	{command,args,env}	{url,headers,transport}, canonical
opencode	opencode.json	root mcp.<name>	{type:"local",command:[cmd,...args],enabled,environment}	{type:"remote",url,enabled}
pi	none	—	—	skipped
qwen-code	settings.json	mcpServers.<name>	{command,args,env}	http {httpUrl} · sse {url}
vscode-copilot	<project>/.vscode/mcp.json	servers	{type:"stdio",command,args,env}	http byte-preserved; sse skipped
zed	settings.json	context_servers.<name>	{command,args,env}	http {url,headers}; sse skipped

Gotchas

• Portability skip. A server whose command or args carry ${CLAUDE_PLUGIN_ROOT} is silently dropped on every config-merge backend — the token expands only inside Claude Code. Doctor's MCP check then reports "no portable mcp servers to register" instead of naming a server. Write a bare executable name. See Plugin tree.
• ${AGENTGEAR_CLIENT} expands instead of skipping. Each backend substitutes it for its own client id in the server's command/args. See Plugin tree.
• pi ships no MCP surface at all; its ~/.pi/agent/mcp.json belongs to a third-party extension, so agentgear writes nothing there.
• Skipped transports are silent by design. antigravity http, and goose/zed/vscode-copilot sse, have no faithful landing, so those servers are dropped rather than written to the wrong transport. A remote server that never appears in the tool traces back to one of these.
• A same-key entry elsewhere can outrank ours. e.g. crush honors a same-name server in $XDG_DATA_HOME/crush/crush.json at higher precedence, which agentgear never writes.

See also

• Capabilities — the index and the portability filter.
• Agent backends — the shared MCP renderers and how to add a backend.
• Harness comparison — the harness-first grid.