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

Annotations already declare readOnlyHint and openWorldHint, so the description's job is to add context, which it does: it names the data source (TomTom), the geographic limit (US only), and the semantics of the reading (live speed vs free-flow). It says nothing about rate limits, quota, or freshness lag, but the core behavioral picture is clear.

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 short sentences, front-loaded with the core purpose and immediately followed by the use case and the alternative. No 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 no output schema, the description carries the return-value burden and does say what the reading represents (speed vs free-flow). Full schema documentation covers the inputs. Units and per-point response shape are left implicit, but nothing an agent needs in order to choose and call the tool 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?

Schema description coverage is 100%, so the schema already explains place, center precedence, and the up-to-10 points format. The description adds only the interpretive detail that each point is resolved to its nearest road, which is useful but thin beyond the baseline.

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: live traffic speed compared against free-flow speed, on the road nearest each point, US-only, sourced from TomTom. That is concrete enough to separate it from incident, camera, and route-planning siblings without opening a 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?

Gives an explicit trigger ('is the bridge backed up right now') and names the alternative (plan_trip) for a whole drive. It does not address other near-neighbors such as get_incidents or check_route, so routing is clear but not exhaustive.

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