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

Annotations only declare readOnly and openWorld, so the description carries most of the burden and does well: it discloses sort order (latest first), one-record-per-company-per-action deduplication, and that the payload includes service-observed diffs (actions added, changed, removed from the CAA list). The change-tracking disclosure is genuinely useful behavior an agent could not get from the schema. It loses a point for not stating pagination or how to retrieve records beyond the 200 cap.

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 question-style opening is front-loaded and immediately frames the query the tool answers, with the field list and caveats following in a logical order. The single long sentence that enumerates returned fields is dense and drags, though no sentence is genuinely filler.

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 an output schema present, 100% parameter coverage and annotations set, the description only needs to add scope and behavior — and it does, via national-only scope, ordering, dedup semantics and change tracking. Remaining gaps are pagination behavior past the limit cap and its relationship to caa_action_lookup, both minor against an otherwise rich definition.

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%, including the default of 365 days ago and the 1-200 limit range, so the input schema already documents all three parameters. The description only echoes them ("since a date", "optionally filter by action_type") without adding format, semantics, or interaction detail. Baseline 3 is the correct ceiling here.

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?

The description names a specific regulator, a specific statute, the resource (companies acted against) and the record granularity ("one record per company and action, latest first"). That is far more than a restated title. It stops short of 5 because it never distinguishes itself from the sibling caa_action_lookup, which an agent could plausibly pick for the same question.

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?

It supplies real scope constraints — "National actions only" and an optional action_type filter — which tell the agent when this tool's output is appropriate. What is missing is any routing guidance against the sibling caa_action_lookup or any note on when a date window is too broad. Usage is inferable but not spelled out.

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