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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds meaningful behavioral details beyond annotations: it returns up to `limit` results, restricts to the same country and category, and excludes the input charity. This gives an agent a clear model of the tool's behavior.

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?

Three short sentences, each earning its place: the core behavior, the use case, and an important exclusion detail. The most critical information is front-loaded, 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 simple lookup tool with rich annotations, the description is largely complete. It covers inputs, selection criteria, limit behavior, and exclusion. Since there is no output schema, the return format could be specified a bit more, but 'other charities' is a reasonable description.

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 50%, so the description partially compensates by explaining that `limit` controls the maximum number of returned charities. The slug parameter is described in the schema, and the description reinforces its role as the source charity. This adds value beyond the structured schema.

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?

The description states a specific verb ('return'), a resource ('other charities'), and precise selection criteria ('same country + category' and 'same country + category'). It also clarifies that the input charity is excluded from results, clearly distinguishing this from search_charities.

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 description gives clear usage context: 'Useful for find more like this recommendations.' This implies the intended scenario well. It does not explicitly name alternatives or state when not to use it, so it stops short of a 5.

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