List categories

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read profile is covered. The description adds that counts and category groupings are returned, but this largely overlaps the output schema, and it discloses nothing about cost, caching, or ordering.

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 compact sentences with no filler, and the key value (the returned counts) plus the chaining instruction are front-loaded. The opening is slightly awkward but nothing is wasted.

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?

With an output schema, no parameters, and safety annotations present, the description only needs to say what the tool enumerates and how to use it, which it does. An agent has enough to call it correctly and route the output to list_items.

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?

The tool takes zero parameters, so there is no argument semantics to explain and the baseline is 4. The description correctly implies a no-argument enumeration.

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 the resource (components, blocks, templates and their grouping categories) and that it returns counts, which is a concrete purpose beyond the bare name. It is clear what the tool reveals, though the 'How many…' phrasing is slightly indirect rather than a crisp verb+resource statement.

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 explicitly tells the agent how to consume the result: 'Use the names as the category filter of list_items,' which links this enumeration tool to a concrete follow-up sibling. It stops short of explicit when-not-to-use guidance or naming alternatives like search_items.

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