Model catalog and pricing

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

Annotations already indicate readOnly, idempotent, and non-destructive. The description adds that it reads live catalog data, includes pricing, and requires no API key. No contradiction with annotations; additional behavioral details enrich the agent's understanding.

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 sentences, each earning its place. Front-loaded with the primary action, followed by usage guidance, then clarifying constraints. No wasted words.

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?

Despite no output schema, the description clearly indicates the output content: the Mirai catalog and public USD prices per million tokens. This is sufficient for an agent to understand what will be returned. Annotations cover safety profile.

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?

There are no parameters (schema coverage 100% trivially). Baseline is 4 for 0 parameters. Description does not need to add parameter semantics, and it implicitly conveys the tool's function.

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 it reads the live Mirai catalog and public USD prices per million tokens. It differentiates from siblings: account_status (likely account-related) and call_model (sending a chat). The verb 'Read' and resource 'catalog and pricing' are specific.

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?

Explicitly says 'Use this before choosing a model.' Also clarifies what it does not do ('Does not send a chat') and that no API key is required, guiding the agent when to use this tool versus alternatives like call_model.

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