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

Annotations already cover the safety profile (destructive, idempotent, open-world, non-read-only), and 'WRITE:' is consistent with that. The description adds one genuinely useful behavioral fact — 'Only the fields you pass change' (partial update semantics) — but says nothing about what a settings change does to an existing optimization, nor about required auth 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?

Front-loaded with the operation class and resource, then the field list, then the partial-update rule — three short clauses, no padding. The trailing 'POST /ext-update-route' is endpoint trivia that an agent invoking the MCP tool doesn't need.

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 annotations carrying the destructive/idempotent profile and a fully documented schema, the description supplies the one missing behavioral fact (partial update). The only residual gap is not saying whether changing settings invalidates an already-optimized route.

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 every parameter is already documented including enums and formats. The description's parenthetical field list adds mild value by grouping the mutable fields and using friendly labels (name, date) that map to route_name/route_date, but nothing beyond the 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?

States a specific verb and resource ('change settings of an existing route') and enumerates the mutable fields, making it clearly separable from upper_create_route and upper_update_stop. The 'WRITE:' prefix signals the operation class against read siblings, 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?

'change settings of an existing route' implies the precondition that a route must already exist, which is the main usage constraint. There is no explicit guidance on when to use this versus upper_optimize_route or upper_create_route, and no stated prerequisites.

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