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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true. The description adds no behavioral context beyond listing return fields, which repeats what could be inferred from an output schema that doesn't exist. For a read-only lookup, the safety profile is fully covered by annotations, so this is a significant 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 with no waste, front-loading the core action and then providing usage context. It could be slightly more concise by merging the return-fields list, but overall efficient.

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 lists return fields, which is helpful. However, for a tool with three parameters and only 33% schema coverage, it fails to explain the two undocumented parameters (field_mask, language_code), leaving the definition incomplete for correct invocation.

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 required place_id is covered by the schema description ('Place id, with or without the places/ prefix'), but the other two parameters (field_mask, language_code) have 0% schema description coverage. The description doesn't mention these parameters or their purpose, leaving the agent without guidance on how to use field_mask for response shaping or language_code for localization.

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 states a specific verb ('Get details') and resource ('one known place'), and explicitly identifies the source of the place_id (places_search_text or places_nearby), distinguishing it from siblings like places_nearby and places_search_text.

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?

It gives a clear when-to-use condition ('Use when the user asks for a specific place's phone number, website, opening hours, or rating') and names the sibling tools that produce the required place_id, effectively preventing misuse.

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