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

Annotations already declare readOnly/idempotent/non-destructive, so the description earns credit for adding what they cannot: result ordering (newest first), the two-part response shape, the data-coverage cutoff date, and a per-call cost. It doesn't cover pagination or result-size limits, which keeps it at 4 rather than 5.

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?

Front-loads the core action and result ordering, then adds coverage caveat and cost. Dense but mostly earned; the double-brokering sentence is a bit of an aside yet still helps the agent decide to call it.

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 output schema, the description still explains what comes back (detected changes plus `fmcsa_history` entries with FMCSA date, CarrierVet sighting date, and before/after values) and warns about the historical coverage boundary. That is enough to call it and interpret the result correctly.

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% and the single `dot` parameter already carries format and pattern guidance, so the description adds nothing parameter-specific. Baseline 3 applies when the schema does all the work.

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: lists changes detected in a carrier's FMCSA record across named categories (address, phone, email, authority, insurance, out-of-service), plus a second component `fmcsa_history`. An agent can tell this apart from `lookup_carrier` or `get_risk` by the historical/change-tracking focus, though no sibling is named explicitly.

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 clear context for use ('Recent contact changes are a common double-brokering warning sign') and a real limitation ('History starts on the date CarrierVet began recording, so older changes are not included'), plus cost ('Costs 1 lookup'). It does not name alternative tools or state when not to call it, so it stops short of a 5.

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