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

Annotations already cover the read-only/open-world profile, and the description adds genuinely useful behavior beyond them: the tie-breaking invariant that a route is never 'proven' without a closed landing, the fact that free callers see masked route names, and the equivalence to a known REST view. Pagination, ordering, and rate-limit behavior remain undisclosed.

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-loaded with the resource and its state model, then supporting fields, then the access caveat and REST equivalence — a sensible information order. The sentence 'A route is never proven without a closed landing' partially restates the parenthetical definition of 'proven', a small redundancy.

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 carries the burden of describing returns, and it does list the key fields (last_priced_at, last_landed_at, landed_count, max_age_seconds) plus the state taxonomy. It omits result size, ordering, and whether masking extends to other fields, which are minor for a read-only listing 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% and the single optional access_key is fully documented there, so the baseline of 3 applies. The observation that free callers see masked route names indirectly adds meaning about what the key unlocks, but the description never explains the parameter directly.

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 concrete verb and resource ('List corridors and each route's standing') and even enumerates the three possible standings, so the agent knows exactly what the tool returns. It does not differentiate itself from closely named siblings such as 'coverage' or 'swapeazi_coverage', which an agent could easily confuse it with.

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 only implied: by defining 'proven' as requiring a real price and a closed landing, it signals this is the tool for checking whether routes are actually live. There is no explicit when-to-use statement, no exclusions, and no named alternative among the many overlapping siblings (coverage, assess_route, price_routes, corridor_events).

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