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

Annotations already declare readOnlyHint=true and destructiveHint=false, establishing the safety profile. The description adds meaningful behavioral detail: it aggregates multiple registries, returns specific fields per match, treats UUID queries as exact-id lookups, and references a live count endpoint.

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?

Three information-dense sentences carry the payload: core behavior first, then return fields, then special query semantics. The parenthetical live-count endpoint is slightly extra but still useful and does not bloat the description.

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 two-parameter, read-only search tool with no output schema, the description is complete: it states what is searched, what is returned, how to use special query forms, and which sibling to use next. The agent has everything needed to select and invoke this tool correctly.

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 100%, so the schema already documents both query and limit. The description adds value beyond the schema by explaining that a UUID query behaves as an exact-id lookup and by telling the agent to paste a listing id.

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 uses a specific verb ('Search') and precisely defines the resource: EVERY major skill/MCP registry at once, with concrete examples. It clearly distinguishes itself from siblings by emphasizing cross-registry aggregation and names registry_get_skill as the natural follow-up.

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?

The description gives clear usage context: free-text queries for broad search and UUID queries for exact-id lookups. It also directs the agent to registry_get_skill for fetching full SKILL.md and install metadata, but it does not explicitly enumerate when to prefer this over other search siblings like search_skills or rig_search.

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