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

Annotations already communicate read-only, idempotent, non-destructive behavior, and the description adds useful context beyond that: the credential requirement and the exact fields the caller should expect. It does not specify error cases or formatting, but the annotations lower the burden and the added field list is valuable.

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 description is two compact sentences with no filler; the resource and contents are front-loaded and the required credential follows naturally. Every clause 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 simple one-parameter read-only status tool with no output schema, the description covers the returned data and the required input. It does not explain error behavior or define domain terms like 'states' and 'rail,' but none of these are essential for selecting and invoking the tool correctly.

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% and the buyer_key schema description already states that it is issued to the licensed contact at confirmation. The tool description repeats this requirement without adding format, length, or example details, so it adds no net semantic value beyond the schema.

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 enumerates exactly what the tool reports (states, rail, terms, founding period, counts, credit balance, licence verification) for a registered agency, making the resource and scope clear. It lacks an explicit verb such as 'retrieves' and does not contrast with sibling tools, so it stops 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?

It gives clear context that the tool applies to a registered agency and requires the buyer key issued at confirmation, which implies when it is appropriate to call. It does not explicitly name alternatives such as check_eligibility or register_agency, nor state when not to use this tool, so guidance is implied rather than explicit.

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