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

With no annotations, the description carries the full burden, and it does well: it discloses that the tool only prepares an application, can never submit one, requires a director to act on the registrar's service, has quota-charged register lookups with free cached results, and avoids side effects like filing accounts. It also reveals the first field of the response ('nextAction').

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 longer than average, but it is front-loaded with the key output and each sentence adds useful information about behavior, cost, or input modes. A little domain context (free, 15 minutes, most useful thing) could be trimmed, but it does not obscure the tool's purpose.

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 7-parameter tool with no annotations and no output schema, the description is remarkably complete. It covers input modes, parameter interactions, cost/quota behavior, side-effect safety, jurisdiction support, filing-type limits, and the shape of the answer, leaving no critical gap for an agent deciding whether and how to call it.

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 coverage is 100%, so the baseline is 3, but the description adds substantial meaning: it clarifies the companyNumber vs. manually-supplied-dates modes, explains that periodEnd bounds extra time, notes which jurisdictions have register access, and states that only accounts can be extended while confirmation-statement requests receive an explanatory response.

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 names a specific operation: checking whether a company can still apply for more time, how many days remain, and the late cost if missed. It also distinguishes itself from siblings by stating it never submits an application, links to the registrar's own service, and does not file accounts.

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 for when this tool is useful ('usually the most useful thing to tell somebody who has just found a deadline') and explains two input modes: supply a company number or provide dates yourself. It does not explicitly name alternatives or say when to choose another sibling, but the use case is concrete enough.

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