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

With no annotations, the description carries the burden and does a good job: it discloses the privacy boundary (no company name/number sent), the quota/cache behavior, and the narrative style/audience. It stops short of stating what happens on invalid figures or how 'derived' figures should be prepared, but the core behavioral traits are transparent.

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 sentences, each carrying distinct information: purpose, privacy constraint, and quota/cache behavior. The key purpose is front-loaded and there is no redundant wording.

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?

The description gives the output type (plain-English reading), the audience, the input boundary, and cost behavior, which is sufficient given the fully-described schema. The only ambiguity is what 'derived sheet' means and how it relates to the figures object, but the schema resolves most of the input structure.

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?

The schema already describes all parameters in detail (100% coverage), so the baseline is 3. The description only adds that the figures object is the entire 'derived sheet' sent to the model, which is a mild semantic clarification but doesn't expand on individual parameters.

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 uses a specific verb phrase ('a plain-English reading') and identifies the resource ('a set of figures' / 'derived balance sheet'), the audience, and the output content ('what the derived balance sheet says... anything that needs attention before filing'). This makes the tool's purpose distinct from siblings like check_accounts, which implies validation rather than explanation.

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 implies when to use the tool: before filing, for a non-accountant director, and it notes that only the derived sheet is sent to the model. However, it never explicitly names alternatives or states when not to use it (e.g., versus check_accounts), leaving the routing partly to inference.

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