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

Annotations already establish readOnly=true, idempotent=true, non-destructive, closed-world, so safety is covered. The description adds real behavioral value by disclosing the response contract (funded items, tax note, giving link) and the required input pairing (amount + cadence), which annotations do not convey.

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?

Two sentences, front-loaded with inputs then outputs, with no filler. The parenthetical example list is slightly long but earns its place by concretizing the otherwise abstract notion of 'what a gift funds'.

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 no output schema and only 2 params, the description adequately compensates by enumerating the returned fields and the use trigger. Minor gap: it doesn't clarify how cadence affects the impact estimate or the giving link, which an agent invoking monthly vs once might want to know.

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 50%: amount is documented in the schema, but cadence (enum + default) has no description. The description restates 'cadence (once|monthly)' which the schema already declares via enum, so it adds little semantic meaning beyond confirming the accepted values.

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?

States a specific verb (estimate) plus the resource (donor impact / what a gift funds) and enumerates the concrete return payload: funded items, tax-deductibility note, and a pre-filled giving link. An agent can distinguish this from calculate_va_benefits or match_donor_intent without opening any schema.

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 routes usage: 'Use when a donor asks what a gift funds.' This gives a clear positive trigger, but it names no alternatives (e.g. get_donate_options, match_donor_intent) or exclusions, so the agent must infer which sibling handles adjacent donation queries.

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