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

Annotations already declare readOnlyHint and idempotentHint, lowering the burden. The description adds meaningful behavior: ids survive re-serves (idempotency), return value contents, and error handling for unknown/expired ids with re-search guidance. This goes well beyond the annotations and gives the agent a clear model of what happens.

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 three sentences, each contributing unique information: purpose, id source/stability, and return/error behavior. It is front-loaded with the core action and avoids redundancy with the schema.

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 simple single-parameter lookup tool with an output schema and rich annotations, the description is complete. It covers purpose, id provenance, stability, return content, and error behavior. No significant gaps remain.

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 schema already provides full parameter coverage (100%) including the id format and constraints. The description adds value by naming the exact source tools (geocode, reverse_geocode, search_places, resolve_intersection) and highlighting id stability and determinism, which are not in the schema. This enriches the semantics beyond the schema.

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 uses a clear verb ('Look up') with a specific resource ('place by its stable ThinAir id') and identifies the id format (ta_place_… / ta_intersection_…). It also names the sibling tools that produce these ids, which distinguishes this lookup tool from geocoding and search tools.

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 clear context for when to use this tool: when you have an id from geocode, reverse_geocode, search_places, or resolve_intersection, and want canonical data. It emphasizes the ids are deterministic and safe to store, implying reuse over repeated lookups. It doesn't explicitly state when not to use alternatives, but the context is strong enough.

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