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

The annotations declare readOnlyHint=true and destructiveHint=false; the description reinforces this by explaining the mechanism ('proposal only: nothing changes until cxt_save_route_plan'), which is exactly the context an agent needs to trust that re-optimizing is non-persistent. It also adds the required ITINERARY_PLANNING_ACCESS scope and the underlying endpoint, which annotations do not convey. It stops short of describing the returned proposal's shape or failure modes.

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 short clauses, front-loaded with the action and its precondition, then the safety caveat, then auth and endpoint. Zero filler for an 11-parameter tool.

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 complex planning tool with no output schema, the description covers the two things an agent most needs beyond the schema: that the result is a non-persisted proposal and what permission is required. What's missing is any hint about what the proposal contains or how the optional inputs (input_route_ids, excluded_stop_ids) affect the outcome.

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 high (82%), so the schema already documents route_id, post_date, start_time/end_time, goal, enhanced_routing, and the ID arrays. The description adds only the {postDate} path placement and no semantics for the undocumented fields (is_placeholder, excluded_stop_ids), so the baseline 3 applies.

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+resource ('Re-optimize a single route') with a clear scope qualifier ('after manual changes') that separates it from the bulk planner siblings like cxt_plan_routes and from the order-level cxt_optimize_order_plan. It never names those siblings explicitly, so the distinction is inferred from wording rather than stated.

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?

The phrase 'after manual changes' gives a concrete trigger condition, and '(proposal only: nothing changes until cxt_save_route_plan)' routes the agent to the follow-up save tool. No explicit when-not guidance or discussion of choosing between route-level vs order-level optimization is given.

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