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

readOnlyHint=true already declares this is a safe read, so the description's burden is lower. It adds useful context about optional expansion of related data and the underlying endpoint, but says nothing about not-found behavior, permissions, or response shape.

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 tight sentences with the core action front-loaded and the endpoint as trailing technical detail. No filler.

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 two-parameter read with full schema coverage and annotation-declared safety, this is nearly sufficient. The only missing piece is what happens when the id doesn't resolve, which matters for error handling.

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 both customer_id and expand are already documented; baseline 3 applies. The description restates the expand capability but adds no syntax or format detail beyond the schema's own examples.

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 (fetch) and resource (a single Autumn customer by id) plus the endpoint. The word 'single' implicitly separates it from autumn_list_customers, but it does not name any sibling explicitly, so it lands just short of a 5.

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?

The single-by-id scope implies when to use it versus the list variant, but there is no explicit guidance on alternatives. Notably it never distinguishes itself from the sibling autumn_get_or_create_customer, which is the ambiguous case an agent most needs resolved.

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