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

Annotations declare readOnlyHint=false and idempotentHint=false, and the description proactively explains the apparent discrepancy ('Reads or computes only; not marked read-only because each call is charged'). It also discloses cost ($0.003/call via x402 USDC or card key, first 25 free, failed calls free) and the CC0 data license. This is exactly the kind of context annotations cannot carry.

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 purpose and return fields, then usage, then pricing. Every sentence carries information relevant to invoking the tool correctly. The pricing sentence is somewhat dense, but cost is a real decision input for an agent, so it earns its place.

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 enumerates the returned fields (coordinates, description, country, admin region, population, elevation), covers cost/auth, and clarifies the read-only flag. Nothing material is missing for an agent to select and call this tool.

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 baseline is 3. The description adds value by showing a worked example that pairs 'name' with 'count' (name=Uppsala, count=3), demonstrating how the two parameters interact. It doesn't restate range limits, but the schema already covers those.

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 (find places by name in Wikidata and return coordinates/description/country/region/population/elevation), plus the ordering guarantee ('best match first'). This clearly distinguishes it from sibling tools like weather, sun, or time, which are lookups that consume a location rather than resolve one.

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 guidance: 'Use before weather, sun or distance lookups, or to tell two places of the same name apart.' It names the sibling tools it precedes and states the disambiguation use case. A concrete example (name=Uppsala, count=3) reinforces invocation.

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