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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds genuine context beyond that: the 25-carrier cap and the 'empty = nothing new' result semantics. It does not mention what happens when more than 25 carriers are supplied or how results are ordered, so the extra value is moderate rather than rich.

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 densely packed sentence front-loads the resource and scope, then appends the result-interpretation rule. No filler, no repetition of the title, and 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 two-parameter read-only query with no output schema the bar is low, and the description covers the scope and empty-result case. It is still incomplete on the two things an agent must know to call it correctly: the carrier identifier format and the days default/ceiling, neither of which appears anywhere else.

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 carries the burden, and it does partially: 'last N days' maps to the days parameter and 'up to 25 carriers' corroborates maxItems on carriers. However, it omits the days default (30) and bounds (1-365), and critically never specifies the identifier format expected in the carriers array (DOT vs MC number), which is the highest-value unknown for a 0%-coverage schema.

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 resource (FMCSA events) with a precise scope (last N days, up to 25 carriers) and enumerates the event categories returned (out-of-service orders, authority suspensions, insurance cancellations). An agent can tell what this returns without opening the schema. It stops short of naming or contrasting the siblings new_carriers/vet_carriers, so it is clear but not sibling-differentiating.

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 explicit when-to-use statement or routing against alternatives; the tool reads as a monitoring/alerts feed but the description never says 'use this to check for changes on existing carriers, use vet_carriers to screen new ones.' The only usage-adjacent hint is 'Empty = nothing new,' which is about interpreting results, not about selecting the tool.

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