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

Annotations already declare the safe-read profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the description is not required to restate safety. It adds genuinely useful non-schema context: 'evidence-backed' implies data provenance, and the '$0.10; API key required' clause discloses both cost and authentication needs.

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?

A single front-loaded sentence enumerating the payload, followed by a compact parenthetical for cost and auth. Nothing is wasted, though the parenthetical pricing note tucks practical calling information behind a terse aside.

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?

An output schema exists, so return values need not be explained, and the safety profile is covered by annotations. However, with three undocumented parameters at 0% schema coverage and no routing guidance against a large sibling set, an agent lacks the information needed to filter correctly rather than fetch unfiltered.

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 0%, so the description must carry the burden for 'to', 'from', and 'limit' — and it does not. The origin/destination wording refers to the returned legs, not to how the 'to'/'from' parameters should be populated, and no accepted formats are given.

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 ('Read') and resource ('travel legs') and enumerates the fields returned (origin, destination, timing, mode, provider, distance, linked expense). This is clear enough to separate it from other read tools like get_expenses or get_photos, but it never names a sibling or explains how it differs from get_travel_history, get_trips, or get_movements-related logging tools.

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?

There is no statement of when to use this tool versus alternatives such as get_travel_history or log_movement, nor any prerequisite or scoping condition. The only contextual note is a pricing/auth aside, which is not usage guidance.

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