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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true, so the safety profile is carried by structured data. The description adds nothing about the destructive nature — it does not say that supplied values overwrite what is there (the 'notes substitui o campo notes' nuance lives in the schema, not here) or that omitted fields are left untouched. A partial-update tool with destructiveHint deserves one sentence on overwrite semantics; that is missing.

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?

Two sentences, zero filler: the scope statement comes first, the sibling routing second. Nothing is buried and nothing repeats 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 an 8-parameter mutation tool with no output schema, the definition covers purpose and alternative-selection well, but leaves the agent without a mental model of partial-update behavior — what happens to fields not supplied, and whether this can silently overwrite the client-facing cadastro. Given destructiveHint=true, that gap matters more than in a read 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 description coverage is 100%, and the schema already covers the parts the description omits: phone format with country code, CPF 11 digits vs CNPJ 14 digits, empty string erasing the document. The description's field list adds little beyond what the schema already says, 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?

The description names a specific verb and resource ('Atualiza os dados cadastrais de um contato') and enumerates exactly which fields are touched (nome, e-mail, empresa, CPF/CNPJ, telefone, origem, observações). It also explicitly excludes status/pipeline/dealValue, which is the main ambiguity against its closest sibling, update_contact_status.

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?

It gives an explicit routing rule: use update_contact_status for status/pipeline/dealValue. That is exactly the kind of alternative-naming guidance that prevents mis-invocation. It stops short of addressing other adjacent tools (e.g. link_contact_company for the company association, or add_contact_tag), so it is clear but not exhaustive.

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