Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered; the description nonetheless adds real context: metadata-only content ('no persona text and no skill instructions'), the error envelope shape with recovery guidance, and the guarantee that malformed input never raises a protocol error. Slight redundancy in restating read-only/idempotent/retry-safety, which the annotations already imply, keeps it from a 5.

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?

Front-loaded with purpose and cost ('FREE'), then return shape, then routing guidance, then error behavior — a sensible order. Slightly over-long: the final sentence about read-only/idempotent retry safety largely restates annotations.

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?

Despite an output schema existing, the description still gives the agent the practical return shape and usage of the slug field, plus content boundaries and the error contract. Nothing an agent needs in order to call this correctly and chain it to the right follow-up tool is missing.

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?

Zero parameters, so the baseline is 4, and the description confirms 'Takes no arguments,' which matches the empty schema with additionalProperties false. Nothing further is needed.

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?

States a specific verb and resource ('List every product in the Research Desk line with its included skills') and scopes it to 7 products, which is distinguishable from siblings like get_full_product and get_free_skill. The return shape example makes the output concrete without needing the schema.

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?

Explicitly names when to use it ('when the caller wants to see what this server covers') and names two exclusions with the alternative tools: catalog-wide keyword search belongs to search_catalog, and actionable instructions belong to get_free_skill. It also directs the agent to feed the returned slugs into get_free_skill, get_full_product, or get_full_skill.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.