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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds meaningful context beyond annotations: the release is 'QA-gated', covers '3,678 profiles' and 'IRS tax years 2018 to 2026', and 'counts toward monthly searches'—useful operational and data-scope details.

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 sentences with no filler: the first states the operation and scope, the second gives data coverage, and the third states limitations and quota impact. The core purpose is front-loaded and every sentence 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?

The definition provides release scope, dataset size, covered tax years, explicit exclusions, and quota metering, which is strong context for a search tool. With no output schema, it could describe the return shape, but the absence is a minor gap rather than a blocking one.

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%, so the schema already documents all four parameters. The description reinforces the query parameter format ('full legal name or EIN') and repeats that mission/topic queries are unavailable, but it does not add new parameter-level detail beyond what the schema provides.

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 uses a specific verb ('Look up') and resource ('private foundation') with explicit lookup keys ('full legal name or EIN'), and it adds release scope. It does not explicitly differentiate itself from sibling get_foundation, which may also fetch foundation data by identifier, so it stops short of a 5.

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 excludes mission/topic and grant-purpose searches ('withheld until their source and quality contracts pass review'), telling agents when not to use the tool. However, it does not name alternative siblings that would handle those cases, so it lacks the full when-not/alternatives guidance of a 5.

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