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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false) by disclosing the strict rate limit (a couple per sender per day), the no-retry rule, and the privacy model: the message is forwarded to Patrick's email, not stored, and rate-limit counters are hashed with daily expiry. This is the behavioral detail an agent cannot infer from structured fields.

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?

Four tight sentences, each front-loading a distinct concern: action, authorization precondition, rate-limit/retry behavior, and privacy. No filler or repetition of the schema.

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?

For a non-idempotent outbound-send tool, the definition covers authorization, rate limits, retry policy, and data handling. With no output schema, return values are not needed, and nothing an agent needs to decide or invoke correctly is missing.

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 high (83%), so the schema already documents the required fields and the reason enum. The description adds no field-level syntax or format guidance beyond the schema, so the baseline 3 applies.

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 (send), resource (a short introduction by email), and recipient, on behalf of a person. It is trivially distinguishable from the read-only siblings (get_profile, list_faq, list_skills, list_work) which cannot send anything.

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?

Gives an explicit precondition: only use when the person asked you to contact him and has approved the message. It also states an explicit anti-behavior, 'Do not retry on error,' which is exactly the kind of when-not guidance an autonomous agent needs.

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