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

Annotations establish this is a safe, read-only, closed-world check, so the safety burden is already carried. The description adds useful domain context (overdrawn director loan is supported and produces a CT600A, currency is POUNDS), but does not state what the response contains or how ineligibility is reported.

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?

Three tight sentences: purpose, the enumerated criteria, then the director-loan exception and currency. Front-loaded and every clause carries information.

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 12-parameter eligibility gate with an output schema absent, the description gives the agent enough domain context to interpret inputs and the special loan case. It falls short of describing the verdict/response shape, which is the one remaining gap.

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 only 8%, so the description must compensate, and it does explain the eligibility-relevant inputs: micro-entity limits, single UK trade, dormancy implied by limits, and the overdrawn loan/director-loan edge case. It does not map each of the 12 parameters to semantics, but covers the core business meaning well.

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 precise verb and resource: checks whether a company fits CT600 micro-entity eligibility, and enumerates the conditions (micro-entity limits, single UK trade, no groups/R&D/gains/property). Clearly distinct from sibling compute_ct600 (which computes) and ct600_filing_guide (which guides).

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?

Implied usage as a pre-flight gate before compute_ct600, but the description never explicitly says 'use this before filing' or names alternatives. An agent must infer the ordering from the sibling names alone.

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