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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety bar is low, yet the description still adds real value: it names the return shape (subject line and body) and discloses the BYOK key handling — request-scoped, never persisted or logged. That's meaningful context beyond the annotations. It stops short of describing provider-side failure/rate-limit 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?

Three tight sentences, front-loaded with the action and inputs, followed by the return value and the security guarantee. No filler; every sentence carries 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?

With no output schema, the description correctly supplies the return shape (subject + body) and the key-handling guarantee, and hints at brevity via 'short'. It leaves out error/fallback behavior across the five providers and any length or rate constraints, so it's strong but not exhaustive for a 7-param, nested-schema tool.

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 71%, so the schema already documents most parameters (contact fields, context.tone/notes/reason, provider enum, apiKey). The description only restates the contact/context framing and the apiKey scoping, adding little for model, provider, maxTokens, or temperature. 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 and resource ('Draft a short, personalized cold outreach email') and names the exact inputs (contact + context) and output (subject line and body). It doesn't need sibling differentiation since no sibling generates content, but it also makes no explicit contrast with extract_contact_info or find_prospects, which would have earned a 5.

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 implies the use case (cold outreach with a personalized angle) but gives no explicit when-to-use/when-not guidance, no prerequisites beyond BYOK, and no pointer to any alternative tool. An agent must infer that it should gather contact/context data from the sibling tools first.

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