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

Annotations already declare destructiveHint=true and non-idempotent, and the description adds real context by explaining what gets written and that it syncs address/city/country/coordinates. It stops short of stating whether an existing address is overwritten, which would fully justify the destructive flag.

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 parenthetical and em-dash construction front-loads the core action and then layers conditions. Every clause carries actionable information (prerequisite, role rules) with no 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?

For a mutation tool with no output schema, the description covers what it does, the prerequisite source of place_id, and the per-segment role behavior — everything needed to invoke 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 the schema documents place_id, segment_id, and the role enum. The description goes beyond that by explaining where place_id comes from and when to pass origin/destination versus omitting role for single-location segments, adding conditional semantics the schema does not.

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 ('Attach a Google Place to an ALREADY-EXISTING segment') and clarifies the retroactive scope, distinguishing it from segment_create/segment_update. An agent can tell exactly what it does without opening the schema.

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 gives the when: segments with a venue/name but no address, e.g. imported from a ticket confirmation. It also names the prerequisite data source (place_id from places_search/place_details) and routes role usage per segment type, leaving little to inference.

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