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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds useful behavior beyond that: results come back sorted by value with place names and the publisher of each value, which tells the agent what it will receive. It does not mention rate limits or the 50/300 row cap (left to the schema).

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?

Two sentences, front-loaded with the operation and scope, then the return shape. Every clause carries information — the examples and the 'sorted by value with names and publisher' clause each earn their 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 compensates by specifying the row shape (value, name, publisher) and ordering. All seven parameters are documented in the schema, and the safety semantics are carried by annotations, so nothing an agent needs to call this 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?

Schema description coverage is 100%, including per-parameter examples for variable, child_type and parent_place plus enum and default notes for sort/limit. The description restates the variable/parent/child relationship but adds no syntax, format, or default detail beyond the schema, so the baseline 3 applies.

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 precise verb (compare) plus the exact scope (one statistical variable across every child place of a parent), and the three examples map the abstract scope onto concrete real-world cases. It implicitly separates itself from datacommons_observation (single-entity lookup) and datacommons_find_place/find_variable (ID resolution) by making clear this is a bulk child-place aggregation.

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?

The worked examples (population of all US states, median income of every Texas county, GDP of every European country) make the intended usage clear and actionable. However, it never says when NOT to use it or names a sibling alternative (e.g. datacommons_observation for a single place), so routing is left partly to inference.

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