Update a ProAbono customer (write)

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

With no annotations, the description carries full behavioral disclosure. It explicitly says 'WRITE', explains the upsert side effect, states that only passed fields are modified, and warns about overwriting values the customer may have set through hosted pages. This is unusually transparent for a mutation tool.

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?

The description is concise and front-loaded with 'WRITE' and the core action. Each sentence contributes necessary information: identification, upsert behavior, partial update semantics, and a caution about field ownership. No filler or repetition.

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 write tool with no annotations and no output schema, the description covers the key invocation concerns: what it does, when it creates, how updates behave, and which fields should be avoided. It is slightly incomplete only in that it does not describe the response shape or error behavior, but the 100% schema coverage and detailed behavioral warnings make it sufficiently complete for correct invocation.

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 baseline is 3. The description adds meaningful parameter-level guidance beyond the schema: it clarifies that customer_ref is the shared reference, that fields are only changed when passed, and that name/language should not be passed if the merchant is not the authority. This goes beyond the simple schema descriptions.

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 states the specific action ('Updates a ProAbono customer'), identifies the resource ('customer'), and clarifies the unique identification mechanism ('shared reference'). The upsert behavior also distinguishes it from a plain create, so the agent can tell it apart from create_customer.

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 provides clear context: customers are updated by shared reference, unmatched references trigger creation, and only passed fields are changed. It also gives a strong 'do not pass' warning about name and language fields being overwritten. It does not explicitly name sibling tools as alternatives, but the context is clear enough.

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