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

No annotations are provided, so the description must disclose behavior. It does: mutation, required permission (crm:write), 404 on invalid id, and the domain-specific caveat that CRM membership does not grant email consent. This covers authorization, error, and domain constraints well, though it omits details like idempotency or response format, which are minor for a simple update.

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 three sentences, each with a distinct purpose: core action, permission requirement, and error/consent caveat. It is front-loaded with the primary purpose and avoids fluff. Every sentence earns its place, making it efficient and easy to parse.

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 simple mutation tool with fully described parameters and no output schema, the description covers the essential operational aspects: permission, error handling, and a critical domain rule. It could mention the response format, but that is not necessary for correct invocation. Overall, it is sufficiently complete for an agent to use it 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?

The input schema describes all 5 parameters with simple labels (email, company_id, contact_id, etc.), achieving 100% coverage. The description adds meaningful context by stating that only sent fields change (partial update) and that contact_id must be valid. However, it does not elaborate on each parameter beyond the schema, so it stays at the baseline 3 for full schema coverage.

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 states the action precisely: 'Updates one contact in the tenant CRM' with a specific resource (contact) and verb (update). It distinguishes from sibling tools by emphasizing partial update semantics ('only the fields you send change') and by contrasting with create/delete/get/list siblings. This makes the tool's purpose unambiguous.

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 clear usage context: it requires crm:write permission, explains error behavior for missing/foreign ids (404), and warns that email consent is handled separately in the marketing sub-resource. It doesn't explicitly name alternative sibling tools (e.g., 'use create for new contacts'), but the guidance is sufficient for an agent to decide when to use this tool.

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