list_couriers

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

With no annotations, the description carries the full behavioral burden. 'Show' and 'check' clearly imply a read-only operation with no destructive side effects, which adds transparency. However, it does not disclose whether the credential check calls external courier APIs or what happens when credentials are missing/expired, leaving some behavioral ambiguity.

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 entire description is a single, focused sentence with the main action up front, courier examples in parentheses, and no filler or redundant wording. Every phrase earns its place.

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 low-complexity, zero-parameter tool, the description covers the core information an agent needs: what is listed and that credentials are validated. It lacks only a precise statement of the output shape, such as a list of couriers with active/expired credential status, which is a modest gap given that no output schema is present.

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 has zero parameters and an empty input schema, so there is no parameter gap for the description to fill. The description appropriately focuses on what the tool returns rather than inputs, meeting the baseline for a no-parameter tool.

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 starts with a concrete verb ('Show') and a specific resource ('supported Bangladeshi couriers'), then enumerates the exact couriers and adds the credential-checking function. This makes the tool's purpose immediately obvious and distinguishable from create_parcel, track_parcel, get_balance, and check_fraud_risk without needing to inspect any schema.

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 description implies the intended use: check which couriers are supported and whether credentials are active, likely before creating a parcel. It does not explicitly state when to prefer this tool over its siblings or mention any exclusion cases, so the when-to-use guidance is only implicit.

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