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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds real value by disclosing the return shape (formatted address, lat/lng, place_id, types, plus code) and by clarifying that geocoding is not a prerequisite for directions. It omits rate limits, quota, or key/auth requirements, so it stops short of a 5.

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?

Front-loaded with the core operation, then usage, alternatives, and return values in tight, information-dense sentences. Every clause carries distinct value (routing advice, return shape), with no repetition of the name or filler.

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 by enumerating the returned fields, and it covers both invocation modes plus sibling routing. For a read-only 5-parameter tool with annotations covering safety, nothing an agent needs to call it correctly is missing.

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 documents address/latitude/longitude but does not state that they are alternatives selected by direction of the lookup; the description supplies exactly that conditional semantics ('forward: pass address', 'reverse: pass latitude and longitude'). field_mask and language_code remain undocumented in both places, which is the only gap.

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 ('convert an address to lat/lng' and the reverse) and explicitly names both operation modes, so an agent immediately understands the bidirectional behavior. It is clearly distinguishable from siblings by naming places_search_text and directions directly.

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?

Gives explicit when-to-use ('the user needs coordinates or a normalized address, or before places_nearby') and when-not-to-use ('To find businesses use places_search_text; directions accepts addresses directly, so geocoding first is not required'). Nothing is left to inference about routing between this and its siblings.

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