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DeepSeek Harness

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DeepSeek Harness (dsh) is an open-source agent harness from DeepSeek AI built on an everything-is-a-plugin architecture. The @youdotcom-oss/dsh-plugin package wires You.com into it at three levels in one install: You.com becomes the backend for dsh’s native web_search tool, four You.com MCP servers mount, and three bundled skills teach the model when to reach for each tool.

DeepSeek Harness is in developer preview. Compatibility-breaking changes are expected across both dsh and this plugin before general availability.

Install the Plugin

1

Add the Plugin to a Profile

Run the dsh CLI’s plugin command against the web profile:

dsh plugin --profile web add @youdotcom-oss/dsh-plugin

The first run initializes the profile if needed, installs the package, and appends it to the profile’s bundle list.

2

Set Your API Key (Optional)

Keyless web_search and the you-discover and you-docs MCP tools work with no credentials. The rest reads YDC_API_KEY from the launch environment. Set it before starting dsh:

export YDC_API_KEY="<YDC_API_KEY>"

Get a key at you.com/platform.

3

Start dsh and Try It

dsh web
Search the web for the latest DeepSeek model releases and summarize what changed.

DeepSeek Harness lists the bundled skills in the session’s skill catalog. When a task matches one, the model loads its full instructions with the built-in skill tool, then the native web_search tool answers through You.com with typed, citable sources.

What the Plugin Installs

Web search. web_search answers through You.com—keyless out of the box, higher limits with an API key. web_fetch keeps DeepSeek Harness’s built-in HTTP provider by default; opting into You.com’s extracted page content needs an API key (see Configuration).

MCP servers.

ServerEndpointAuth
you-discoverhttps://api.you.com/mcp?profile=discoverNone
you-financehttps://api.you.com/mcp/financeYDC_API_KEY
you-researchhttps://api.you.com/mcp/researchYDC_API_KEY
you-docshttps://you.com/docs/_mcp/serverNone

Skills.

SkillUse it for
you-researchChoosing between agent-led searching and a single cited you-research call
you-financeFinance questions through the You.com finance research MCP tools
you-discoverFinding the right You.com API, MCP server, or SDK for a project you’re building

Keyless Tier

With no YDC_API_KEY in the environment, web_search runs through You.com’s free profile: 100 queries per day, no account. The you-discover and you-docs MCP servers work keyless too. You.com-backed web_fetch and the research and finance servers need a key.

Configuration

Every field defaults when omitted, so the shipped patch needs no config. To change one, add a config block to the youcom-skills row in your profile’s cordis.patch.yml. Fresh profiles ship that file as an empty [] list, so replace it with the row:

- id: youcom-skills
  config:
    apiKey: sk-…
    numResults: 10
    includeNews: false
FieldTypeDefaultMeaning
apiKeystring$YDC_API_KEYAPI key. An explicit value here takes precedence over YDC_API_KEY in the launch environment. Empty enables the keyless search fallback and disables fetch.
baseURLstringhttps://ydc-index.ioBase endpoint for /v1/search and /v1/contents. A path prefix (for a proxy) is preserved.
freeSearchURLstringhttps://api.you.com/mcp?profile=freeKeyless MCP endpoint used when apiKey is empty. No fetch equivalent exists.
numResultsnumberserver defaultDefault result count when a request carries no maxResults.
includeNewsbooleantrueMerge news results into search sources alongside web results.
knowledgestringoffRequest licensed knowledge results alongside web and news, surfaced as the search result’s answer content with data-provider credits appended. Only "core" is accepted.

To opt web_fetch into You.com as well, set fetchProvider: youcom on the web row of your own patch. Patch config is a whole-row replacement, so restate searchProvider: youcom on the same row.

Example Prompts

Use you-research to compare WebAssembly and JavaScript for performance-critical browser apps. Cite sources.
Search for the latest MCP specification changes, then fetch the spec page and summarize the authorization section.
Use you-finance to summarize NVIDIA's most recent quarterly results.
Use you-discover to find the best way to add You.com search to a TypeScript agent built on the Vercel AI SDK.

Keep the Plugin Updated

dsh plugin forwards to pnpm in the profile directory, so the standard verbs work:

dsh plugin --profile web update @youdotcom-oss/dsh-plugin

Remove it with dsh plugin --profile web remove @youdotcom-oss/dsh-plugin.

A running profile keeps the bundle set from startup, so restart the profile after adding, removing, or updating a bundle. Ordinary edits to the profile’s cordis.patch.yml hot-reload without a restart.

Troubleshooting

Install Node.js, then run npx @deepseek-ai/dsh web to start the harness without a global install. See the DeepSeek Harness README for the full setup.

The plugin subcommand forwards to pnpm, which must be on PATH. Node.js ships Corepack. Run corepack enable to activate it, or install pnpm directly, then retry the install.

The plugin’s peer-dep ranges track dsh’s prerelease line. Update dsh and retry the install, or pin the plugin version to match your build.

The free profile carries a daily request cap. Set YDC_API_KEY in the launch environment, or add apiKey to the plugin config, to lift the cap.

you-research and you-finance send Authorization: Bearer $YDC_API_KEY. Without a key the servers still mount but expose zero tools rather than blocking the rest of the profile. Set the key and restart dsh.

Confirm the plugin is in the profile’s bundle list with dsh web --dump-config, which shows the @youdotcom-oss/dsh-plugin layer. Then restart dsh.

Resources

Agent Skills

What each You.com skill does and how to install skills in other agents.

MCP Server Reference

Endpoints, authentication, and the full tool reference.