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

With no annotations, the description carries the transparency burden. It discloses the return type ('Returns one review object at the top level'), enumerates possible fields ('review_id, review_text, rating, and user_name when available'), and warns about 'Additional upstream fields may appear.' It also notes the cost of 2 tokens. While it doesn't explicitly state read-only behavior, 'Get' implies it, and the disclosed details are solid.

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 four brief sentences, each providing essential information: purpose, prerequisite, return shape, and cost. It is front-loaded with the main verb and resource, and every sentence earns its place with zero fluff.

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 one-parameter lookup with an output schema, this description covers all necessary aspects: what it does, how to obtain the input, what the output looks like, and even the token cost. The output schema handles return-field details, so no additional explanation is needed.

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% (review_id has a description), so baseline is 3. The description adds significant semantic value by explaining where the ID comes from: 'from a place reviews response.' This goes beyond the schema's generic 'Google Maps review identifier' and helps the agent correctly source the parameter.

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 the tool's function: 'Get details for one Google Maps review.' It specifies the resource (Google Maps review) and the action (get details). It also differentiates from siblings like place_reviews and place_details by requiring a review_id from a place reviews response, making its scope 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 gives explicit usage context: 'Provide review_id from a place reviews response.' This tells the agent when to use this tool (after fetching place reviews) and where to obtain the necessary input. It doesn't explicitly name alternatives or exclusions, but for a simple lookup tool the guidance is sufficient.

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