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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds behavioral context by enumerating the data sources (IRS 990-PF, web-extracted, 360Giving, CRA T3010, ACRI) and the types of aggregate outputs. It does not disclose potential limitations such as data completeness, but the additions are valuable beyond the annotations.

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, followed by a concise explanation of data sources and outputs, then the parameter selection. Each sentence contributes new information, with no fluff or redundancy. It is appropriately sized for the tool's complexity.

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?

Given an output schema exists, the description does not need to detail return values. It explains the tool's scope, data sources, and parameter usage. It lacks explicit notes on edge cases (e.g., funders with no data), but overall it is complete enough for an agent to invoke the tool correctly.

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 covers 100% of parameters. The description adds a decision rule for choosing between ein and funder_id based on funder type, which is not fully articulated in the schema. It also reinforces the formatting details (hyphens allowed). This extra guidance meaningfully assists the agent.

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 'Get comprehensive giving statistics for a funder,' clearly stating the verb and resource. It further specifies what the statistics include (lifetime totals, focus areas, geographic distribution, trends) and the data sources used, effectively distinguishing it from siblings like get_funder_profile or get_foundation_grants.

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 explicit guidance on when to use each parameter: 'Pass ein for US 990 foundations, or funder_id for non-990 funders.' This provides clear context for tool invocation, though it does not explicitly contrast with alternative tools or state exclusions.

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