VAT projection

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

Annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds no additional behavioral context, such as return format, error behavior, or side effects. The statement 'Requires projectionstart' is redundant with the schema's required field list, providing no new behavioral insight beyond annotations.

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 a single, front-loaded sentence that immediately states the action and resource, followed by the key requirement. There is no wasted wording, and it is appropriately sized for a simple read operation with comprehensive schema documentation.

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?

This tool has 7 parameters, 3 required, and no output schema. The description does not explain the return value's structure or any behavior beyond the basic action, which is a significant gap. With no output schema, the description should provide more context about what the figure represents or how it is calculated, but it remains minimal.

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%, so the baseline is 3. The description adds minimal semantic value beyond the schema: it mentions 'VAT code or VAT group', which is already detailed in the vat_code property. It does not elaborate on the meaning of 'projectionstart' or the 'type' parameter, leaving the schema to carry the burden, which it does adequately.

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 clearly states the tool returns a 'projection VAT figure' for a VAT code or group, which is a specific verb-resource pair. It distinguishes itself from siblings like banana_vat_balance and banana_vat_budget by focusing on 'projection', though it could more explicitly differentiate from the generic banana_projection tool.

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 only mentions that 'projectionstart' is required, which is a prerequisite, not a usage guideline. It provides no guidance on when to use this tool versus alternatives like banana_vat_balance or banana_projection, nor any scenarios where it is preferred. No exclusions or alternatives are mentioned.

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