list_customers

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

No annotations are supplied, so the description carries the behavioral burden, and it discloses the backing store (customers.yaml), which implies a simple read of local data. It does not explicitly state that the call is read-only and side-effect free, nor anything about ordering or emptiness, though the low-risk nature of a zero-argument directory read limits the exposure.

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 with the resource and the file it reads stated first, followed by the actionable cross-reference. Nothing redundant or padded.

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 zero-argument listing tool with an output schema provided, the description contains what an agent needs: what is listed and how the resulting customer_id is consumed. Only the explicit read-only/no-side-effect statement is missing.

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?

The tool takes zero parameters, so the baseline is 4; there is no parameter meaning that could be added. The description's only semantic contribution is explaining that the returned customer_id is the value to feed into issue_invoice.

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 names the resource (customer directory / customers.yaml) so it is clear this returns a customer listing, and the customer_id reference ties the output to the rest of the workflow. The verb itself is implicit in the noun 'directory' and carried mostly by the tool name, so it falls short of a fully self-contained verb+resource statement, but it is far from tautological.

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 a downstream usage hint (use customer_id in issue_invoice) but never says when to call this versus siblings like lookup_company or get_supplier, nor what preconditions apply. Usage is only implicitly derivable from the fact that it is a zero-argument directory listing.

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