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

With no annotations, the description carries the full burden. It discloses that results are sorted cheapest first and that prices are cached snapshots, which is useful. However it doesn't state permission/auth needs, rate limits, or what happens with no reachable destinations, leaving gaps for a read tool.

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?

Three compact sentences, front-loaded with the core behavior and sort order, followed by usage context and an efficiency note. No filler; each sentence earns its place.

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 simple 2-param read tool with full schema coverage and no output schema, the description covers purpose, sort order, usage context, and a pricing caveat. It is nearly complete, missing only auth/error behavior, which keeps it from a 5.

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 schema already documents both 'from' and 'limit' with format, units, and default. The description adds no parameter detail beyond what the schema provides, so 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+resource (returns destinations reachable from one origin) and adds a distinguishing detail (sorted cheapest first). It implicitly contrasts with find_cheapest_fare by framing inspiration vs one specific pair, but does not name the sibling outright, so it falls short of a 5.

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?

Gives concrete when-to-use cues: 'when the user asks where they can fly cheaply from a city, or wants inspiration rather than one specific pair.' This clearly delineates it from find_cheapest_fare, though it doesn't explicitly name the alternative tool or state exclusions.

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