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

Annotations are minimal (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false), so the description carries the behavioral burden and does it well: it may execute, it may return a pre-filled payload, it returns candidates when confidence is low, it never overrides explicit values, and max_cost affects execution. No contradiction with annotations.

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?

The description is compact and front-loaded with the core behavior, and the final flow line adds the confidence condition. The flow is slightly redundant with the earlier 'either executes or returns a payload' sentence, but every sentence still contributes useful information.

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 6-parameter tool with nested objects and no output schema, the description covers the key execution paths, fallback behavior, and explicit-value handling. It lacks a precise description of the candidate return structure, but it is otherwise complete enough for an agent to decide whether to call route and how to consume the pre-filled payload.

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 baseline is 3. The description groups tool, skill, model, and input into 'dimensions you already know' and restates the no-override guarantee, but this mostly reinforces what the schema already says rather than adding meaningful new parameter semantics.

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 action and resource: sending a natural-language intent through a router that fills unknown dimensions and produces an executable call or a ready-to-run use_tool payload. It is not a tautology and is clearly distinguishable from the sibling use_tool because route returns a pre-filled payload rather than directly invoking a known tool.

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 description gives clear context for when to use route — when you have an intent and want blanks filled — and tells the agent it can supply known dimensions as constraints. It names use_tool as the downstream consumer of the pre-filled payload, though it stops short of an explicit 'use this instead of X when...' exclusion.

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