Exa Search MCP for DeepSeek Harness

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A third-party plugin that brings Exa — the neural web search and fetch engine — into DeepSeek Harness (dsh). It connects to Exa's hosted MCP endpoint (Streamable HTTP) through the MCP client bridge that ships with the dsh CLI, and registers Exa's tools as native agent tools under the exa namespace.

mcp__exa__web_search_exa   ·  mcp__exa__web_fetch_exa
mcp__exa__web_search_advanced_exa  ·  mcp__exa__agent_run   (with an API key)

• Zero install footprint: no code runs in the dsh process — the upstream is Exa's official hosted endpoint.
• Pure configuration bundle: one patch layer, no build step, no runtime API.
• Never touches your deepseek-harness installation; it only adds one row to the composed cordis.yml.

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Quick Start

1. Install

Option A — install as a plugin bundle (recommended, requires pnpm):

npm install -g pnpm
dsh plugin --profile web add github:MicroHEROX/dsh-exa-mcp
dsh web

Verify after a github: install — when the route to github.com is unstable, a github: (git) install can silently fail or finish with an un-synced dsh.profile.bundles (local link:/file: installs are unaffected). Verify and fix in one step:

# check: does the bundle layer appear?
dsh --profile web --dump-config | grep -A2 "== dsh-exa-mcp"
# if not (or to fix preemptively), append the bundle to the profile manifest:
node -e "const fs=require('fs');const p=process.env.DSH_HOME+'/profiles/web/package.json';const j=JSON.parse(fs.readFileSync(p,'utf8'));if(!(j.dsh.profile.bundles||[]).includes('dsh-exa-mcp')){j.dsh.profile.bundles=[...(j.dsh.profile.bundles||[]),'dsh-exa-mcp'];fs.writeFileSync(p,JSON.stringify(j,null,2)+'\n','utf8');console.log('fixed: dsh-exa-mcp appended');}else{console.log('already present');}"

The timing issue is reported upstream (Discussions #656); --patch overlays are never affected.

Option B — one-off overlay, no install:

dsh web --patch /path/to/dsh-exa-mcp/cordis.patch.yml

Option C — keep it permanently without installing: merge the single insert block from cordis.patch.yml into $DSH_HOME/profiles/<name>/cordis.patch.yml (or $DSH_HOME/cordis.patch.yml for every profile).

Install behavior: pnpm installs git dependencies through the files field, so docs/ is not installed into your runtime — only cordis.patch.yml is. The docs live in this repository.

2. Provide an Exa API key (optional)

The hosted endpoint works anonymously on Exa's free tier (rate-limited, basic tools only). To lift limits and unlock advanced search / Exa Agent, create an API key and set it in the environment:

export EXA_API_KEY="your-key"        # macOS / Linux
$env:EXA_API_KEY = "your-key"        # Windows PowerShell

The plugin auto-detects the key at load time: EXA_API_KEY set → sends x-api-key; unset → anonymous. Never put the key into any patch file.

3. Verify

1. Start dsh web (with the bundle or overlay applied).
2. Wait a moment for initial discovery (it is asynchronous).
3. Ask: "Use Exa to find the latest release notes of the DeepSeek Harness project on GitHub and summarize them."
4. Confirm the model called mcp__exa__web_search_exa (and web_fetch_exa for full text) and answered from the results.

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What This Plugin Does

• Connects https://mcp.exa.ai/mcp via @deepseek-ai/dsh-mcp-client (streamable-http transport), the official bridge shipped with the dsh CLI.
• Registers every tool Exa advertises under the spec-compliant name mcp__exa__<tool>; re-syncs automatically on tools/list_changed notifications.
• Auto-authenticates: attaches x-api-key only when EXA_API_KEY is present (graceful anonymous fallback — no broken undefined header).
• Tunes the bridge for search workloads: toolCallTimeoutMs: 180000 for long research tasks; reconnect policy left at bridge defaults.
• Follows dsh plugin conventions exactly: bundle manifest (dsh.bundle.patch), patch-layer composition, per-id override (mcp-exa), !!js config expressions only.

What This Plugin Does NOT Do

• Does not download, host, or supervise any Exa server — the upstream is Exa's hosted endpoint.
• Does not implement OAuth login (https://mcp.exa.ai/mcp?login) — the dsh MCP bridge has no OAuth flow; use an API key.
• Does not bridge MCP resources or prompts — the harness only consumes MCP tools.
• Does not choose Exa plans, manage billing, or store your API key — the key lives in your environment only.
• Does not modify your deepseek-harness installation — installing/uninstalling only touches $DSH_HOME/profiles/.

Routes That Work

Route	How
Anonymous search + fetch	Do nothing — free tier, rate-limited, 2 tools
Full tool set (advanced search, Agent)	Set EXA_API_KEY + restart; whitelist Agent via ?tools= (below)
Tool whitelist / default search type	Override the mcp-exa row's url with ?tools=web_search_exa,web_fetch_exa,agent_run or ?defaultSearchType=fast (see docs/API.md)
Multiple MCP servers	Add more mcp-client rows with unique serverName values
Hot reload	Edit the row in a patch layer — HMR reconnects without process restart
Uninstall	dsh plugin --profile <name> remove dsh-exa-mcp — profile and base bundles stay intact

Routes That Do NOT Work (by design)

Route	Why not
OAuth login flow	dsh mcp-client does not implement the OAuth handshake — use an API key
MCP resources / prompts from Exa	The harness bridges tools only
Per-request auth switching	The EXA_API_KEY decision is made at config evaluation (startup / HMR), not per call
Using the same patch twice (bundle installed and --patch)	dsh fails loud with duplicate loader entry id: mcp-exa — pick one method
API key in patch files	Keys belong in environment variables; committing them is a leak

Uninstall

Bundle installs (installed via dsh plugin add):

dsh plugin --profile <name> remove dsh-exa-mcp

Verify nothing remains:

dsh --profile <name> --dump-config | grep -c "dsh-exa-mcp"   # expect 0

If installed from a github: spec during an unstable network window, remove can leave a dangling dsh-exa-mcp entry in dsh.profile.bundles, which makes the profile fail to boot with cannot resolve profile bundle "dsh-exa-mcp". Fix by removing the entry (node, no BOM):

node -e "const fs=require('fs');const p=process.env.DSH_HOME+'/profiles/<name>/package.json';const j=JSON.parse(fs.readFileSync(p,'utf8'));j.dsh.profile.bundles=(j.dsh.profile.bundles||[]).filter(b=>b!=='dsh-exa-mcp');fs.writeFileSync(p,JSON.stringify(j,null,2)+'\n','utf8')"

Overlay / manual installs (no bundle):

• --patch overlays: just drop the --patch <path>/cordis.patch.yml flag from your start command — nothing persists.
• Patch merged into a profile file: delete the mcp-exa block (or the whole insert list) from $DSH_HOME/profiles/<name>/cordis.patch.yml, or $DSH_HOME/cordis.patch.yml for every profile.

Optional: unset EXA_API_KEY in your environment if you no longer use Exa.

Uninstalling never touches your deepseek-harness installation or any other bundle — it only edits the profile directory under $DSH_HOME.

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Version Compatibility

Component	Version	Notes
dsh-exa-mcp (this plugin)	0.1.0	See releases
DeepSeek Harness CLI (@deepseek-ai/dsh)	≥ 0.1.0-rc.5, tested on 0.1.0-rc.7	The CLI ships the @deepseek-ai/dsh-mcp-client bridge this bundle mounts
MCP bridge (@deepseek-ai/dsh-mcp-client)	^0.1.0-rc.7 (resolved from the dsh CLI)	No separate install needed
Exa MCP endpoint (mcp.exa.ai/mcp)	server 3.2.1 (probed 2026-08-14)	Exa-managed; may change without notice
MCP protocol version	2025-06-18	Negotiated automatically
Node.js	tested on v24.16.0; Node ≥ 22 recommended	dsh itself does not declare an engines range
Platform	Windows / macOS / Linux	Config-only bundle; no platform-specific code

dsh is in developer preview and iterates rapidly. After upgrading dsh, re-run the verification steps from docs/SOLUTIONS.md.

Security

• The only secret involved is EXA_API_KEY, read from the environment at load time; it is sent to Exa as the x-api-key header and never written to any file by this plugin.
• No third-party code executes inside the dsh process — the plugin is declarative configuration over the official bridge.
• This repository contains no keys, no local paths, and no machine-specific data.

License

MIT. Not an official DeepSeek or Exa product.

Acknowledgements

Built for DeepSeek Harness by DeepSeek AI — the "everything is a plugin" harness built on Cordis. Powered by:

• Exa MCP Server — the hosted web search endpoint
• Model Context Protocol SDK — the protocol this plugin speaks through
• @deepseek-ai/dsh-mcp-client — the MCP bridge used by this bundle
• Cordis and its plugin ecosystem — the framework under dsh

Thank you to the DeepSeek Harness team and every open-source project this work builds on.

Documentation

• Project documentation · Glossary · API reference · Solutions & pitfalls
• DeepSeek Harness: https://github.com/deepseek-ai/deepseek-harness
• Exa MCP docs: https://exa.ai/docs/reference/exa-mcp