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

Goes well beyond the annotations: it discloses patch semantics, that omitted fields are untouched, that `null` clears optional fields/subdocuments, that `email` cannot be cleared, the exact 404 behavior, and critically that every successful update fires a `customer.updated` webhook to external endpoints. The destructiveHint/openWorldHint annotations are confirmed and enriched with concrete consequences.

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-loaded with purpose, then discovery guidance, then semantics, then the bolded side-effect warning — a sensible ordering with no filler sentences. Slight redundancy with the schema's per-field patch/null notes costs it the top mark.

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?

An output schema exists so return values need not be described, and the description covers the remaining unknowns an agent needs: partial-update semantics, clearing behavior, error behavior, and the external webhook side effect. Nothing material is missing for an 8-parameter mutation 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 coverage is 100%, so the schema already documents most parameters; the baseline is 3. The description adds cross-field semantics not present in any single schema entry — the global 'only supplied fields change' rule, whole-subdocument patch/clear behavior, and the email-clearing exception — earning a modest bump above baseline.

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 ('Update the editable details of a customer record') with the account scope named. It also routes the agent to the sibling `list_customers` for ID discovery, so it is distinguishable from at least one adjacent tool without opening a 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?

Gives an explicit prerequisite ('Use `list_customers` first if you need to discover the customer ID by name or email'), which is actionable context for a tool requiring a customerId. It does not state when NOT to use this tool (e.g. use get_customer for read-only inspection), so it stops short of full when/when-not guidance.

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