calculate_vat_reverse

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

No annotations exist, so the description must convey behavioral traits. It states the tool extracts and returns values, implying a read-only calculation. However, it does not explicitly declare safety (e.g., 'no side effects'), permissions, or rate limits. For a calculator, this is adequate but not exemplary.

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 two sentences with a cross-reference, all front-loaded with the core purpose. No redundant information, every sentence serves a function. Excellent conciseness.

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?

Given the tool is a simple calculator with complete parameter descriptions in the schema and an existing output schema, the description adequately covers purpose, inputs, outputs, and references related tools. It is fully sufficient for correct invocation.

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?

Input schema has 100% coverage, so baseline is 3. The description repeats the inputs ('TTC amount, VAT rate %') and adds output context ('Returns HT, VAT amount'), but does not clarify the meaning of TTC/HT or provide additional constraints beyond the schema. This adds marginal value.

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's purpose: 'extract the VAT and net price from a TTC amount' and 'back out tax from a gross invoice'. It uses specific verbs and identifies the resource. However, it does not explicitly differentiate from sibling VAT calculators like calculate_vat_generic, which could cause selection ambiguity.

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 provides a clear usage scenario ('Use to back out tax from a gross invoice'), which implies when to use. But it does not specify when not to use this tool versus other VAT calculators, nor does it mention alternatives. The reference to list_bundles for related calculators is helpful but indirect.

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