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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered. The description adds genuinely useful context beyond that: the catalogue is broader than the listed tools, and the result (names plus short descriptions) is a discovery artifact that must be followed by tool_schema/run_tool rather than executed directly. No rate limits or result-count behavior are disclosed, which keeps it short of a 5.

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 short sentences, fully front-loaded: capability first, then the when-to-use condition, then the follow-up workflow. Every sentence carries information an agent needs to act, and none is redundant.

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 single-parameter, read-only search tool with annotations covering safety, the description supplies the missing pieces: what is searched, what comes back, and the mandatory next steps. With no output schema, it still tells the agent the shape of the response, so nothing needed to invoke or use the tool correctly is absent.

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% and the schema itself documents the keyword syntax, example, and matching rule (matched against names and descriptions, any term may match). The description's 'by keyword' only restates that, so it adds nothing beyond the structured field — the baseline 3 for full coverage 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?

States a specific verb and resource ('searches the full catalogue of available tools by keyword') and names the return payload ('matching tool names with a short description'). This clearly differentiates it from the sibling tools, all of which operate on models, prices, or providers rather than on the tool catalogue itself.

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 states the triggering condition ('when no directly-listed tool fits the task — many tools are available but not listed') and then routes the agent through the follow-up chain: call tool_schema for the picked tool, then run_tool to execute. Both alternatives are named siblings, leaving nothing to inference.

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