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

Annotations already provide readOnly, idempotent, and non-destructive signals. The description adds meaningful behavioral context beyond annotations: it is deterministic ('the same intent always routes the same way'), non-transactional, and returns an explicit empty route with 'unroutable: true' instead of a silent default. It does not mention auth or rate limits, but those are not critical for this tool.

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 front-loaded with purpose, includes realistic examples, and clearly separates routing behavior from transaction behavior. Some redundancy exists between the prose and the 'Returns:' section, and the erroneous final example keeps it from a perfect score.

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?

The description compensates for the lack of an output schema by listing the returned fields (platform_id, label, why_matched, score, entry_points) and the empty-route case. It covers when to call, what to do next, and deterministic behavior. The invalid example is the main gap.

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 adds helpful examples of free-text intent values and explains that the result includes entry_points for next steps. However, the closing example 'call federation_search with arguments {}' conflicts with the required 'intent' parameter and adds no meaningful limit 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 uses a specific verb ('Route'), identifies the resource ('natural-language intent'), and names the output ('ranked platform(s)'). It clearly distinguishes itself from siblings by positioning this as the entry-point router: 'the first thing to call'.

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 explicitly says to call this first and explains the next step: 'you then act on that platform with the chosen tenant.' It also clarifies what the tool does not do ('This returns a ROUTE, not a transaction'). It does not explicitly name alternatives or exclusions, but the intended usage context is clear.

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