nonprofit_fetch_nonprofit_by_ein

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

Without annotations, the description carries full burden. It states 'Read-only. No side effects. Idempotent' and details cache duration, source verification, and a feedback mechanism for inadequate responses.

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 main purpose and includes all necessary details, though slightly verbose. Every sentence adds value, but some consolidation could be achieved without losing information.

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 has an output schema, but the description lists return fields (name, revenue, etc.) and mentions source and cache. This is complete for a simple lookup tool, covering input, output, constraints, and error handling steps.

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 0%, but the description fully documents the 'ein' parameter: format (9-digit with/without dash), examples, and required status. This adds critical meaning beyond the schema's vague 'type: string'.

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 clearly states 'Fetch IRS 990 filing data for any US nonprofit by EIN', specifying the verb (fetch), resource (IRS 990 data), and identifier (EIN). It distinguishes from the sibling tool 'nonprofit_search_nonprofits_by_name' by noting when to use each.

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?

Explicitly says 'Use this when you have the exact EIN. Use nonprofit_search_nonprofits_by_name instead when you only have a name.' Also provides context about verified sources and caching behavior.

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