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

Annotations already indicate readOnlyHint=true and openWorldHint=false, so the description correctly states it's read-only. It adds value by explicitly stating no payment or provider side effect, and mentions the returned metadata fields (capability, family, provider, example_input). This goes beyond annotations, though not exhaustive about pagination, but with 0 parameters and read-only hint, it's sufficient.

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?

The description is three sentences, front-loaded with the main action and purpose, then differentiates from sibling, then adds side-effect and return details. Every sentence earns its place; no fluff.

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?

Given the simplicity (0 params, read-only, no output schema), the description is nearly complete. It covers purpose, usage context, side effects, and return metadata. What's missing is explicit mention of pagination or potential large payload, but for a listing tool with no parameters, this is a minor gap. The context is well-covered.

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 has 0 parameters, so the schema provides no parameter documentation. The description compensates by clearly stating the output metadata fields (capability, family, provider, example_input), which gives the agent context on what the listing will contain. Since there are no parameters, this 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 clearly states the tool's purpose: to list every replay-verified capability. It also differentiates from siblings by mentioning that it's for exact identifiers and examples, while search is for fuzzy intent. This is specific and distinguishes it from the sibling 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 explicitly states when to use this tool (inspect the catalog, obtain identifiers, copy example inputs) and when not to (for fuzzy natural-language intent, use search_verified_capabilities instead). This is excellent guidance for an agent to choose correctly.

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