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

Annotations already mark the tool read-only and idempotent, and the description adds meaningful behavioral context: the cause is the NTEE group of the recipient, the results reflect actual giving history, and searches do not count toward monthly search limits. This goes well beyond the structured hints by explaining what the data represents.

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?

The description is front-loaded with the core purpose, then adds necessary nuances about data source and recipient attribution. The long cause list is functional since no enum is provided in the schema, and the note about monthly search counts is a relevant operational detail. Every part serves a clear purpose.

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 four parameters, detailed cause enumeration, and clarifying notes on state semantics and search quotas, the description is largely complete. It does not explicitly describe the shape of the returned funder list, but the purpose sentence makes the result set obvious enough for an agent to invoke and interpret the result. Minor gap only.

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?

Although the schema already describes all four parameters, the description enriches them significantly: it lists every valid cause name with its NTEE letter, explains that state applies to the recipient rather than the funder, and gives a concrete example like 'Education' or 'B'. This reduces ambiguity that the schema alone would leave open.

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 opens with a specific verb and resource: "Find the private foundations that have given to recipients in a cause area," immediately distinguishing this from generic funder search tools. It further clarifies that it reports actual giving by recipients based on IRS NTEE major groups, not what a funder says it funds, which uniquely positions it among siblings.

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 clearly states what the tool is for—finding funders by cause area optionally limited to a state—and adds context such as "Historical filing evidence, not an open call." It does not explicitly name alternative sibling tools or say when not to use them, but the intended use case is strongly implied and actionable.

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