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

With no annotations, the description carries the full burden, and it does add real behavioral context: 'Free lookup... No key or payment,' which tells the agent no auth is needed. It says nothing about rate limits, result ordering, or whether the headline score is cached/live, so the disclosure is partial.

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 dense, front-loaded sentences that cover purpose, cost model, use case, and follow-up tools with no filler. The parenthetical parameter list makes it slightly crowded but still efficient.

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?

No output schema exists, and the description compensates by naming the returned fields ('id and headline reliability score'). With no annotations and 75% schema coverage, it is largely self-sufficient; only the limit parameter and any ordering/pagination behavior remain undescribed.

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 75%, so most parameters are already documented in the schema. The description restates q, endpoint and category semantics but adds little syntax or format detail beyond the schema, and omits the limit parameter entirely. Baseline 3 is appropriate.

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 states a concrete verb and resource ('find a tool's id and headline reliability score') and enumerates the three lookup keys (q, endpoint, category), so an agent knows exactly what it returns. It does not, however, differentiate itself from the close sibling registry_search_tools, which sounds like an overlapping discovery tool.

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 gives explicit context ('check a tool before your agent pays it') and a next-step chain ('follow with registry_tool_badge or registry_tool_detail'). It stops short of saying when NOT to use it or how it differs from registry_search_tools.

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