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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds one behavioral trait beyond that -- unknown category values return the category list rather than failing -- but says nothing about ordering, pagination, or how errors on the primary path behave.

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, no filler, with the core purpose front-loaded and the fallback behavior second. Nothing could be removed without losing 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 one-parameter, read-only lookup with no output schema, the description covers purpose, the parameter's nature, and a non-obvious fallback path. The only real gap is the missing contrast with sibling tools, which is in a different dimension.

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% with the slug format and an example ('broker_mcp') already documented in the schema. The description only adds the indirect semantic that unrecognized values are tolerated, which is a minor increment over the structured field.

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 specific verb and resource ('List every tool in a category'), which is clear enough to separate it from get_tool and search_tools despite never naming them. The purpose is unambiguous, but it stops short of explicitly contrasting itself with the siblings that also surface tools.

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 offers one concrete calling pattern -- pass an unknown category to enumerate categories -- which is a useful discovery trick. However, it never says when to prefer this tool over search_tools or get_tool, so the primary routing decision is left implicit.

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