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

Annotations only declare destructiveHint=true; the description adds the important behavioral fact that this is a partial (patch-style) update where unspecified fields are preserved, which prevents accidental full overwrite. It also names the underlying endpoint (PUT /api/4/customers/{id}). It does not cover auth requirements, error behavior for an unknown id, or whether the updated record is returned.

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 compact sentences: the field list and partial-update rule come first, then the API mapping. Every clause carries information; no padding or repetition of the title.

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 mutation tool with only a destructiveHint annotation and no output schema, the description covers the fields and partial-update semantics but omits what happens on invalid customer_id, whether the response returns the updated customer, and any permission requirements. Adequate to call correctly, but not complete.

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 the schema already documents all seven parameters including the legal_type enum and the 0-100 discount range. The description merely names the fields in prose, adding no syntax, format, or constraint detail beyond the schema. 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 (update) and resource (customer) and enumerates the mutable fields (name, email, legal type, tags, discount, marketing consent). This is clearly distinguishable from create_customer, get_customer, and update_order among siblings.

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?

Implies usage (modify an existing customer) and the partial-update rule 'Only the fields you pass change' tells the agent it need not resend all fields. However, there is no explicit when-to-use vs alternatives guidance, e.g. that fetching via get_customer first is prudent, or that create_customer is the tool for new records.

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