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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds useful scope about what data comes back (contact details, terms, autopay, credit hold, metadata) but says nothing about auth requirements, error behavior for a missing id, or pagination/expansion options.

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?

A single dense sentence that front-loads the core purpose and ends with the route; no filler. The field list is long but each entry earns its place by telling the agent what the response contains.

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?

With no output schema, the description compensates by enumerating the notable returned fields, which is exactly what an agent needs to judge relevance. Missing only edge-case behavior (unknown id, permissions), which is minor for a read-by-id endpoint.

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% and the schema itself documents the id as 'numeric; not the customer number'. The description only echoes 'by id', adding no syntax or format detail beyond the schema, so the 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 and resource ('One customer by id') plus the HTTP route GET /customers/{id}, and enumerates the fields returned, so the agent knows exactly what it retrieves. It does not explicitly contrast with the nearby siblings get_customer_balance or list_customers, but 'by id' does implicit work in separating it from the list tool.

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?

'by id' implies the lookup-by-identifier use case and the single-customer scope, but the description never states when to prefer this over invoiced_get_customer_balance or invoiced_list_customers, nor any prerequisites. Usage is inferable rather than stated.

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