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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: countries are derived from steps the user adds, and it requires the user's Cotlet API key with access to the app. That auth disclosure is not in the annotations and is valuable for invocation.

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?

The purpose is front-loaded, but the second sentence largely restates the first ('countries visited, kilometers, trips and steps' appears twice), adding length without new information. Sized acceptably, but one sentence is 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 parameters and no output schema, the description carries the burden of describing what comes back and does enumerate the four figures, plus the auth requirement. Only the repeated phrasing and the absence of explicit when-to-use guidance keep it from being fully complete for its complexity.

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?

The tool takes zero parameters, so there is no syntax for the description to document and the baseline is 4. The description correctly does not invent parameters, and briefly notes the figures come from the user's profile.

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 ('Get travel stats') and then enumerates exactly what is returned: countries visited, kilometers, trips, and steps. An agent can separate this profile-level aggregate from siblings like polarsteps_get_trip or polarsteps_list_trips without opening any schema.

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 description implies the scope ('the Travel stats on your profile') which suggests profile-level aggregation rather than per-trip data, giving implied usage. However, it never explicitly says when to prefer this over polarsteps_get_trip or list_trips, and provides no exclusions or prerequisites for invocation.

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