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

With no annotations, the description carries the full burden. It states the tool calculates and returns specific fields, which implies a pure computation with no side effects. However, it does not explicitly confirm read-only behavior or mention any important traits like idempotency. The provided output structure adds some value.

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?

Two sentences: one for purpose and output, one for related tools. No unnecessary words. Front-loaded with essential information. Highly efficient.

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 presence of an output schema (implicitly via description) and 100% param coverage, the description adequately covers purpose, return fields, and tool relationships. Lacks details on error handling or complex scenarios but is sufficient for a straightforward calculator tool.

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 description adds no new meaning to parameters. All four parameters are fully described in the schema. The description does not clarify units beyond 'EUR' or constraints beyond schema definitions, so no extra 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: 'Calculate interest savings from early partial loan repayment'. It specifies the output fields, making the intent unambiguous. The reference to list_bundles for related calculators helps differentiate from sibling tools.

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 usage for computing early repayment savings but lacks explicit guidance on when to use vs alternatives. There is no mention of prerequisites, edge cases, or when not to use this tool. The reference to list_bundles is weak guidance.

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