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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds value by enumerating exactly what data the read surfaces and by noting the required credential for access, which is useful behavioral context beyond the schema.

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 concise sentences with zero filler. The returned data list is front-loaded, and the prerequisite is stated in a single closing sentence. Every element 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 single-parameter, read-only status tool with no output schema and rich annotations, the description adequately conveys the purpose, the required input, and the scope of returned data. It loses one point because domain terms like 'states' and 'rail' are not elaborated, which could leave an agent unsure of their meaning without additional context.

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%: the sole parameter buyer_key is already documented as 'Issued to the licensed contact at confirmation'. The description repeats essentially the same information rather than adding detail like format, length, or how to obtain it. Baseline 3 is appropriate since the schema carries the semantic weight.

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 clear resource ('a registered agency') and a specific verb implied by 'status' — returns a defined list of fields: states, rail, terms, founding period, queued/delivered counts, credit balance, and licence verification. This distinguishes it from sibling tools like 'register_agency' or 'check_eligibility', though it does not name them explicitly.

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 scopes usage to 'a registered agency' and states a hard prerequisite — the buyer key issued at confirmation. This gives an agent a clear condition for when the tool applies, distinguishing it from registration or eligibility flows. It lacks explicit exclusion guidance (e.g., 'not for unregistered agencies'), but the context is clear enough.

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