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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context (result type is Nominatim JSONv2, addressdetails defaults to true) but says nothing about rate limits, result ordering, or what happens when an id is invalid. Adequate but not rich.

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 and short, but the worked example 'W34633854,N123,R456' and the phrase 'comma-separated OSM ids' appear twice, near-verbatim, which is wasted space. The addressdetails default is also duplicated from 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?

An output schema exists, so return values need not be explained, and all five parameters carry schema documentation. Combined with annotations covering safety, the description is nearly complete for correct invocation, with only the geocoding_search contrast left implicit.

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 description coverage is 100%, so the schema already documents all five parameters. The description restates osm_ids and addressdetails verbatim from the schema rather than adding new meaning (e.g., max id count, behavior when a type prefix is wrong). Baseline 3 is correct.

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 and resource ('Returns typed Nominatim JSONv2 places for comma-separated OSM ids'), including the exact input format with a worked example. It distinguishes itself from geocoding_reverse by name, though it never contrasts itself with geocoding_search, so sibling differentiation is only partial.

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 routes the agent away from this tool for reverse geocoding ('Use geocoding_reverse to retrieve reverse geocode coordinates'), which is actionable. It gives no explicit when-to-use condition for the lookup against geocoding_search, but the OSM-id input requirement implicitly scopes usage.

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