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The Add tool directory uses bundled MCP server metadata and an optional local catalog. Instance owners can enable online updates in Settings → Tool discovery and supply a registry URL. Online discovery is off by default and has no default URL. Custom MCP setup remains available independently of the directory. Directory entries suggest a server endpoint and authentication methods. They never connect an account, copy credentials, change an existing endpoint, or enable tools. Connecting remains an explicit action for the selected agent’s own account under the identity guardrail.

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Deployment settings and offline use

Setting either online environment variable makes the entire online section environment-managed and read-only in the dashboard. Setting only a registry URL keeps online discovery off; set both variables to enable it through deployment configuration. Invalid configured URLs fail startup even when discovery is off; startup validation performs no DNS lookup or HTTP request. Local-file configuration is independent of that section. An offline deployment can set MESH_TOOL_DISCOVERY_ENABLED=false and optionally mount a local catalog. It makes no online registry requests, including after an online catalog was previously cached. Metadata precedence is local file, online catalog when enabled, then bundled entries. A stable ID or endpoint appears only once; earlier sources win. This directory does not change MCP transport policy. Private MCP destinations still require the separately planned internal trust policy.

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Publish or maintain a catalog

Bundled metadata lives in internal/integration/mcp_presets.json. Update that single data file through the normal pull request process. Any operator can publish the same JSON as a static HTTPS resource, for example at https://registry.example.com/v1/servers.json, or copy it into an offline installation. Hosting the resource is an operator deployment task. The v1 catalog is a JSON array with this entry shape:
Version the distribution path, such as /v1/servers.json; there is no envelope or schema_version field. This small curated format is not the official MCP Registry API. An operator can transform another registry into this format. IDs are stable lowercase letters, digits, dots, hyphens, or underscores, begin with a letter or digit, and have at most 80 characters. IDs and endpoints must be unique within each document. Labels have at most 80 characters and descriptions at most 1,000. auth_methods lists oauth, bearer, or both, without duplicates; recommended_auth must be one of those methods. Older catalogs omitting the recommendation use the first method. bearer means an API key or bearer token entered by the operator. Do not include credentials, account identifiers, scripts, or tool schemas. Unknown fields are rejected. Documents contain at most 200 entries and 1 MiB of JSON. Endpoints and registry URLs use HTTPS without user information, query strings, fragments, or custom ports. Online registry DNS answers must all be public addresses, checked and pinned immediately before dialing. Fetches send no agent credential, cookie, or account metadata and follow no redirects or environment proxies. Online fetches have a five-second timeout. A successful document or HTTP 304 is cached for one hour; failures retry after five minutes. ETags support conditional refresh. Refreshes run in the background when a local or last-good catalog is available, so those reads return immediately. A cold online read without either source waits for the shared refresh, up to the fetch timeout; canceling one reader leaves the bounded refresh available to other readers. The next catalog read applies a changed registry URL or discovery-off setting: it cancels the old refresh and prevents a late response from replacing the new source. After a read with discovery off, re-enabling starts a fresh lookup on the next read. A failed, oversized, or invalid update preserves the last valid document and reports a warning. A malformed local file likewise preserves the last valid local document. These caches are process-local: after a restart, Formation uses the bundled catalog and configured local file until another valid online response arrives. A catalog failure does not affect saved connections.

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Operator API

All responses require normal session or API-token authentication. The catalog API returns Cache-Control: no-store; server-side metadata caching is independent of browser authentication. An agent operator cannot change instance discovery settings or use another agent’s catalog route without a grant. New metadata fields do not confer authority on the remote publisher.