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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, and the description adds real value on top: what the returned routes contain (dead ends, dated prices, account/bot requirements), a suggested verify-first plan, and an explicit prompt-injection warning that route text is untrusted data. The A/B statistic is promotional rather than behavioral, but the safety framing is substantive. A 4 rather than 5 because it never discusses result staleness limits or what happens when no routes match.

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?

Front-loads the trigger condition ('Call this BEFORE...') and packs return contents, the verify-first recommendation, and the safety caveat into a compact block. The long enumerated list of use cases and the 57-73% statistic add length without much decision value, but nothing is genuinely misleading or redundant.

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?

With no output schema, the description steps in to describe what comes back (working sites, blockers, dead ends, dated prices, a verify plan) and how to treat it safely. Combined with full schema coverage and rich annotations, an agent has everything needed to decide to call it and interpret results.

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%, with each of query, region, and limit documented in the schema itself, so the schema carries parameter semantics. The description only adds the notion of 'similar tasks' and regional preference indirectly, adding little beyond the structured fields. Baseline 3 is appropriate.

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: it returns routes left by other agents for similar tasks, including which sites work, which need accounts, dead ends, and dated prices. The scope is concrete enough that an agent knows it is a search over prior agent findings. It stops short of explicitly distinguishing itself from the sibling get_route, which an agent would have to infer.

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?

Explicitly says to call this BEFORE researching or comparing sites and enumerates concrete triggering situations (supplier search, quotes, listing/launching, sign-up flows). That is unusually clear timing guidance. It does not name alternatives such as get_route for fetching a single known route, nor state when not to call it.

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