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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile needs no restating. The description adds only the returned field name, which the output schema already carries, and says nothing about rounding, percentage vs decimal convention, or formula assumptions.

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 tight sentences; the operation and its inputs come first, and the cross-reference pointer is relegated to the end. No filler.

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 two-parameter calculation with a full output schema and rich annotations, this is nearly sufficient. The one meaningful omission is the gross-vs-net distinction that would let an agent choose confidently among the several rental-yield siblings.

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% and both parameters document their EUR units and positive-value constraints. The description merely restates 'property price and monthly rent' without adding semantics beyond the schema, so the baseline 3 applies.

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 specific verb and resource ('Calculate gross rental yield') and names the two inputs used. The 'gross' qualifier implicitly separates it from calculate_rental_yield_net, but it never explicitly contrasts with calculate_rental_yield or calculate_rental_profitability, so sibling differentiation is only partial.

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?

Usage is implied by the wording rather than stated. The pointer to list_bundles for 'immobilier' calculators is discovery navigation, not guidance about when to pick this over calculate_rental_yield or calculate_rental_yield_net.

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