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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=true, openWorldHint=true, idempotentHint=false), and the description usefully adds a boundary they don't convey: credentials are rejected. It says nothing about update semantics, though — whether changes are a partial merge or full replacement, whether omitted fields are cleared, or why a 'destructive' write is reversible or not.

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 short sentences, ~20 words, no filler. The mutation scope is front-loaded and the credential exclusion follows as a supporting constraint rather than burying the lead.

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 needn't be explained, but for a destructive, open-world mutation with 0% schema coverage and a nested object plus an unexplained required request_id, the description is thin. It should have covered update semantics, the request_id's role, and any required permissions or preconditions.

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 0%, so the description must compensate and it only half does: 'name, email or address' maps to three of the nested `changes` fields. The required `request_id` (which looks like an idempotency key, yet idempotentHint is false) is never mentioned, and partial-vs-full update of `changes` is unaddressed.

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 with scope: 'Update the Stripe customer's billing name, email or address.' That clearly names the resource (Stripe billing profile) and the mutable fields, which distinguishes it from most update_* siblings by resource. It stops short of explicitly separating it from the nearest lookalike, update_account, so an agent must still infer which mutator to reach for.

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?

'Payment credentials are never accepted here' is a real exclusion that steers the agent away from using this as a payment-method mutator. However, it never says where to go instead (e.g. create_billing_portal) nor states the precondition that an existing billing profile/customer must exist, so the guidance is implied rather than actionable.

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