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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real value absent an output schema by previewing the return payload (year range plus load timestamp). It stops short of saying what an empty or never-loaded pack looks like, which is the one behavioral edge an agent might hit.

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?

Two sentences, no filler, with the scope-and-contents statement front-loaded ahead of the routing advice. Every clause carries information.

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 zero-parameter read with no output schema, the description supplies exactly the two things the agent needs: what comes back and when to call it. Annotations handle the safety contract, so nothing material is missing.

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 nothing for the description to disambiguate and the baseline of 4 applies. No parameter language is needed or missed.

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 resource ('what FARS fatal-crash data this pack has loaded right now') and enumerates the exact contents: earliest year, latest year, last-loaded timestamp. That precision separates it from the analysis siblings fars_state_fatalities and fars_vehicle_makes without needing their schemas.

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 an explicit call condition ('Call this before fars_state_fatalities/fars_vehicle_makes if unsure a given year is covered') and names both alternatives. The agent knows exactly when this tool should precede another call.

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