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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the enumeration of returned data domains, which is genuinely useful given there is no output schema. It does not describe error/not-found behavior for an invalid ref, which is the remaining gap.

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?

Two sentences, zero waste: the content summary comes first, the required input provenance second. Nothing extraneous and nothing important buried.

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?

With no output schema, the description compensates well by listing the data domains returned. A brief note on missing/invalid ref behavior would make it complete for a lookup tool, but an agent has enough to call it correctly.

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%, so both parameters are documented in the schema, including the deprecation note on labId that the description omits. The description only reiterates that labRef comes from find_labs, adding no syntax or format detail beyond the structured field.

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+resource (get details for one lab) and enumerates the returned content domains (address, phone, hours, walk-in policy, at-home collection, visit instructions, prices). 'for one lab' plus the reference to find_labs clearly separates it from the sibling list tool.

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 instructs to pass the labRef returned by find_labs, which establishes the correct call sequence and prerequisite. It doesn't state when not to use it (e.g., for bulk retrieval) or what happens with a stale ref, but the positive routing is clear.

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