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

Goes well beyond the annotations by disclosing the read-modify-write mechanics, the fact that the CRM replaces the whole record while only passed fields change, that tags replaces rather than appends, and that no message is sent – exactly the context destructiveHint/idempotentHint cannot convey. It stops short of describing error behavior (e.g., invalid contact_id) or response shape.

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?

Five short sentences, zero padding: mode marker first, then partial-update semantics, then the tags caveat, then the non-effect, then the endpoint. Every sentence carries distinct 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?

For a 24-parameter destructive mutation with no output schema, the description covers the risky parts (overwrite semantics, tags replacement, no messaging) and the underlying PUT path. Gaps remain around failure modes and what comes back, which is acceptable given no output schema but still a small hole for a destructive 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?

With 24 parameters and only 50% schema coverage, the description compensates by explaining the global update semantics ('only the fields you pass change', 'passing a field overwrites its old value') and the special replace behavior of tags. It does not touch the many undocumented per-field params, but the schema covers patterns/enums and custom_fields.

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 ('change fields') plus scope ('existing contact') and front-loads 'WRITE:', which cleanly separates it from revampcrm_create_contact and revampcrm_get_contact without needing the 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?

Makes clear this applies to an existing contact only and rules out a side effect ('does not email or message the contact'), but never explicitly names the sibling to use for creation or reading, so the agent must infer the routing.

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