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

With no annotations, the description carries the full behavioral burden. It usefully discloses that the lookup is FREE, returns only the top 3 matches, and includes city, state, and 501(c) type, but it omits read-only confirmation, matching behavior, auth needs, and error/empty-result 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?

The description is a single front-loaded sentence fragment with no wasted words. The key action, scope, search keys, result limit, and returned fields are all packed efficiently.

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 tool is simple and has no output schema, so describing the top-3 return fields is helpful. Still, with no annotations and 0% schema description coverage, the description is not fully complete: it leaves the state parameter unexplained and creates ambiguity by mentioning EIN when no EIN parameter exists.

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 0%, so the description should compensate for both parameters. It mentions lookup by name or EIN but the schema has only name and state, and the state parameter is never explained; the EIN mention is not reconciled with the 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 uses a specific verb ("Find") and resource ("US nonprofit/charity"), and states the search keys and returned fields. It is clear enough to distinguish this as a lookup tool, though it does not explicitly differentiate itself from siblings like financials or prospect_list.

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?

Usage is implied by "Find a US nonprofit/charity by name or EIN," so an agent can infer this is for nonprofit lookups. However, it gives no explicit when-to-use guidance, exclusions, or comparison to the sibling tools financials and prospect_list.

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