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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by enumerating the outputs (best options, best deductible, break-even point, worst case, saving) and clarifying the ranking cost basis, which matters since there is no output schema.

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 that front-load the ranking operation and then list the returned artifacts. Efficient, though the second sentence is a slightly long run-on enumeration.

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 14-parameter comparison tool with no output schema, the description usefully covers what the tool ranks and what it returns. It stops short of explaining key parameter dependencies (e.g. that municipality_bfs comes from find_postcode or that visit counts drive cost estimates), but is broadly complete.

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 schema already documents all 14 parameters with enums, ranges and examples. The description adds no parameter-level syntax or format detail beyond what is structured, so the baseline of 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 ('Rank every insurer, model and deductible for one person') with the exact cost basis ('full yearly cost for 2027 (premiums plus the bills they pay themselves)'). This is precise enough to distinguish it from the sibling tools (a letter drafter, a postcode lookup, a deadlines reference).

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 mention of 'the saving against their current insurance' implies you should supply current_insurer/current_premium for comparison, but there is no explicit when-to-use guidance, no exclusions, and no routing to siblings like switching_deadlines or draft_switch_letter. Usage is implied rather than stated.

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