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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds valuable behavioral context: it does not count against the rate limit, and it clarifies that generated_at is response time, not the age of a source price tick. It also enumerates the fields returned. This exceeds what annotations provide, though it doesn't discuss error behavior or edge cases.

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 concise, with no filler. It front-loads the main purpose, then provides usage guidance and a clarification about generated_at. Every sentence earns its place, and the structure flows logically from purpose to usage to a subtle caveat.

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 zero-parameter health check tool with no output schema, the description is complete. It explains what the tool reports, when to use it, and a key nuance about timestamps. An agent has all necessary information to call it correctly and interpret results.

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 zero parameters, so there is nothing to document beyond the schema. The baseline for 0 parameters is 4, and the description does not need to compensate for any missing parameter information. It correctly omits any parameter details because there are none.

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 reports feed liveness and freshness, listing specific fields (upstream connection, seconds since last price frame, board size, market coverage, walk errors). It is distinct from sibling tools like get_coverage or get_live_odds, which focus on data content rather than health. The verb 'get' and resource 'health' are specific and unambiguous.

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?

The description provides explicit guidance on when to call: before describing any data as current/fresh and after a 503 error. It also notes that the tool does not count against the rate limit, which is an important usage consideration. This goes beyond just describing what it does and gives clear invocation context.

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