list_couriers

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

With no annotations, the description carries the behavioral transparency burden. It discloses a read-only operation through verbs like 'Show' and 'check', and clarifies that credential status is verified. It does not mention auth requirements or rate limits, but for a zero-parameter listing tool this is a minor gap rather than a serious omission.

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, well-structured sentence front-loads the main action and resource, then adds the credential-checking detail. There is no filler, redundancy, or unnecessary explanation.

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-parameter, no-output-schema, simple read-only tool, the description is complete enough for an agent to invoke it correctly. The only minor ambiguity is what 'spatial services' includes, but this does not block correct usage.

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 input schema has zero parameters and 100% schema coverage, so there is no parameter documentation burden. The description still adds value by indicating what the tool reports: supported couriers, spatial services, and active credentials.

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 uses a specific verb ('Show') with a clear resource ('supported Bangladeshi couriers and spatial services') and adds a second distinct function ('check which credentials are active'). It is immediately distinguishable from siblings like track_parcel, create_parcel, and get_balance, which perform different operations.

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 gives clear context for when to use the tool: when an agent needs to discover supported couriers, spatial services, or active credentials. It does not explicitly name alternatives or exclusions, but none of the sibling tools serve the same discovery purpose, so the routing is unambiguous in this toolset.

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