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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile needs no restating. The description adds real behavioral context beyond that: a Pro tier entitlement requirement and a hard 'minimum 3 characters' constraint on the query. It does not mention pagination or result limits, keeping it from 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?

Front-loaded with purpose, then the return contents, then the hand-off tool, then the arg list. Every sentence earns its place, and the Args block is justified rather than redundant because the schema has zero parameter descriptions.

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 an output schema existing, the description usefully previews the return shape (IDs, sire/dam for disambiguation, career starts) and closes the workflow loop to get_runner_profile. The Pro tier gate and query minimum length are the kinds of constraints an agent needs before calling, and both are present.

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 description coverage is 0% and there are no enums in the schema, so the description carries the full burden — and it does: query (partial name, min 3 chars), race_code with its three allowed values and the default of 'gallops', and country with four allowed codes. This supplies value the schema does not.

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 ('Search for a runner (horse/greyhound) by name'), names the resource domain, and distinguishes itself from the sibling get_runner_profile by clarifying that it returns IDs rather than full stats. An agent can pick between the two without opening either schema.

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?

Gives clear context (search by partial name) and an explicit next step: 'Use the returned runner ID with get_runner_profile() for full stats.' That routing is genuinely helpful, but there is no stated when-not-to-use or comparison against other lookup siblings, so it stops short of a 5.

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