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

With only destructiveHint=true in annotations, the description carries useful extra weight: it flags 'MUTATES Accelo data', specifies the wire format (form-encoded), and describes the return envelope { meta, response }. This is consistent with the annotation rather than contradicting it, though it omits side effects like whether duplicates are rejected or required auth scopes.

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?

Front-loads the mutation warning, then the endpoint, then the caveat, in four tight sentences with no filler. Every clause conveys something actionable.

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?

There is no output schema, and the description compensates by naming the return shape and the mutation semantics, so an agent knows what it gets back. It could go further on partial-failure or required-field behavior, but nothing essential for a correct call 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 description coverage is 100%, so every parameter is already documented at the schema level, which sets the baseline at 3. The description adds no per-parameter meaning beyond that, and the free-form 'fields' passthrough object is not explained any further in prose.

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 ('creates a new contact (a person)') and even names the concrete API surface (POST /api/v0/contacts). The parenthetical '(a person)' cleanly disambiguates it from the create_company sibling 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?

The affiliation note is real usage guidance: it tells the agent that company linkage is NOT set here and must go through POST /api/v0/contacts/{id}/affiliations. That is a clear when-not plus a named alternative path. It stops short of explicitly contrasting with get_contact/list_contacts, so it is strong but not complete routing guidance.

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