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

Beyond the annotations, the description discloses that existing drivers are replaced, that every id must be an active team driver, and that an optimized route is reset to needs_optimization: true – a significant state side effect an agent must know about.

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?

Three tight sentences, front-loaded with the write semantics and pruning constraint, then the validation rule, then the side effect and endpoint. 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?

For a two-parameter mutation with no output schema, the description covers the key prerequisites, destructive replacement behavior, and the required re-optimization step. Nothing material is missing for correct invocation.

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%, so the baseline is 3; the description still adds value by specifying that driver_ids come from upper_list_drivers and must be active drivers on the team, which the schema does not express.

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 states a specific verb and resource ("assign one or more drivers to a route") and immediately clarifies the replacement semantics, which distinguishes it from additive siblings like upper_share_route_to_drivers. An agent can tell what this does without opening the 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?

It names the source for driver ids (upper_list_drivers) and the required follow-up (run upper_optimize_route again after assignment resets optimization). It does not explicitly contrast with upper_share_route_to_drivers, so the guidance is clear but not complete on alternatives.

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