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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds useful context about the required credential (buyer key) and what data is returned, but does not disclose error behavior for missing/invalid keys or any rate limits. Given the strong annotation coverage, this is acceptable but not exceptional.

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 sentence that front-loads the resource ('For a registered agency') and then compactly lists all returned fields, ending with the input requirement. There is no redundancy or filler, though the dash of field names could be slightly more structured.

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?

With no output schema, the description compensates by enumerating the return fields thoroughly. The input requirement is stated, and the tool is a simple read-only status check, so no complex orchestrations are needed. It lacks edge-case behavior, but for a straightforward status retriever this is mostly sufficient.

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 schema already documents buyer_key as 'Issued to the licensed contact at confirmation.' The description reinforces this by mentioning the key requirement but adds no new semantic detail beyond the schema. Baseline 3 applies because the schema carries the burden.

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 data the tool returns ('states, rail, terms, founding period, queued and delivered counts, credit balance, and whether the licence was verified'), giving a specific clear resource. However, it uses no leading verb ('Gets', 'Returns'), relying on the title 'Agency status (buyers)' to convey the action. Sibling names like check_eligibility are not directly similar, so no explicit differentiation is needed.

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 states the prerequisite ('Requires the buyer key issued at confirmation'), which tells an agent the key is mandatory. It does not explicitly state when to use this tool versus check_eligibility or data_use_terms, but the status-read purpose is implied strongly enough by the detailed return list.

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