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

Annotations already cover readOnly/destructive/openWorld, yet the description adds substantial new context: the upstream data source and license (Wikidata, CC0), result ordering ('best match first'), which fields may come back (country, region, population, elevation), and the billing model ($0.002/call, first 25 free, failed calls free). The note that repeats are not free operationalizes idempotentHint=false in concrete terms.

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 action and inputs, then use cases, then cost and safety notes. It is slightly overstuffed: the opening clause largely restates the title, and the billing point is made twice ('charged per call' and 'repeats are not free').

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 helpfully names the returned fields, and pricing plus the read-only guarantee cover the operational concerns. It does not specify the coordinate representation (lat/lon order, decimal precision) or failure behavior beyond 'failed calls free', which leaves a small gap for a tool returning coordinates.

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 both parameters are already documented by the schema, and the description adds little parameter-level detail. The example (name=Uppsala) and 'best match first' give mild ordering context for count, but no format guidance such as coordinate ordering or precision.

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 ('Geocode a place or address to latitude and longitude') and enumerates accepted inputs (city, town, landmark, address name). The forward direction is clear enough to distinguish it from the sibling geocode_reverse without opening either 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 names downstream uses ('for maps, distance, weather or routing') and provides a worked example (name=Uppsala), which gives an agent clear context for selecting it. It stops short of an explicit exclusion like 'use geocode_reverse to go from coordinates back to a place', so the alternative is only implied by the sibling name.

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