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

With no annotations, the description carries the full burden and does so well: it discloses that routing is static keyword-based with no compute ("Prerequisites: none"), enumerates the return fields, and crucially explains that guidance is inlined so "you do NOT need a second resources/read." That behavior/latency note is exactly the kind of trait structured fields don't convey.

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 tier tag, trigger, and prerequisites, which is good. But the body is a dense wall of run-on parentheticals (isochrone, periodic-scheduling, push/pull-to-designer) with no formatting breaks, and the trailing "Scenarios: AB-016, ACB-003, wrong-build-tool" is cryptic and hard to act on, so size partly works against it.

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 high-fan-out router, it covers purpose, trigger, prerequisites, routing branches, and return contents comprehensively, and it even pre-empts the output-schema lookup by describing returns (though an output schema already exists, so that is redundancy rather than a gap). The only meaningful hole is that its own two input parameters remain unexplained.

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 0% and neither parameter is documented: the description never explains what `user_request` should contain or what shape/keys the free-form `context` object expects. The mentions of "required_inputs" and "clarifying_questions" describe outputs, not inputs, so the description does not compensate for the coverage gap.

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 role ("Router / deterministic entry point for ambiguous or open-ended territory requests") and enumerates exactly which workflows it disambiguates (auto_build vs account_build vs direct_build, realign, isochrone, periodic-scheduling, push/pull-to-designer, etc.), so its function is unmistakable. It does not, however, differentiate itself from adjacent guidance/routing siblings such as workflow_advisor or get_guidance, which is the one clarity gap.

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?

Gives an explicit trigger ("When: the user's goal or build type is unclear and you want the correct workflow before acting") plus a scoping adjective ("ambiguous or open-ended") that implies the when-not case. It also names the concrete alternatives for each ambiguous scenario, effectively routing the agent to the correct sibling.

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