Search for a tool that can do something: MCP servers and paid endpoints, ranked by what was measured on each (does it answer, how fast, how much context it costs, do its tools work). No sign-in needed. Use this when you lack a tool for a task.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | ||
| query | Yes | What you need to do, in plain words, e.g. "weather forecast by city" | |
| open_only | No | Only servers that answer without credentials |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish the safe read-only, idempotent profile, so the description's job is lighter. It still adds real context beyond them: the ranking dimensions (does it answer, speed, context cost, do its tools work) and the fact that no sign-in is required.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, front-loaded with the action and followed by scope, ranking criteria, and the usage trigger. The colon-list phrasing is slightly dense but every clause carries information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a three-parameter read-only search with no output schema, the description covers purpose, scope, ranking, and when to invoke. It leaves minor gaps around result shape and the limit parameter, but nothing that would cause a wrong call.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 67%: query and open_only are documented in the schema (open_only as 'only servers that answer without credentials'), while limit is undocumented. The description adds nothing parameter-level beyond loosely echoing the no-credentials idea, so the baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description gives a specific verb and resource ('Search for a tool'), scopes it to 'MCP servers and paid endpoints', and explains the ranking basis. It clearly separates this from the social/invite-oriented siblings, though it never names them explicitly.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It states the triggering condition plainly: 'Use this when you lack a tool for a task.' That is clear context for invocation, but no alternatives or exclusions are named (e.g. when to use tool_details instead).
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.