Create a spec-loop feature

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

Annotations only declare it is a non-read-only, non-destructive, closed-world tool; the description adds real behavioral context: it writes files (skeleton, render, README refresh), can fail with a named blocking feature, and records the owner's reason in the new feature's lifecycle. It stops short of describing the success payload, which the output schema already covers.

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?

Two sentences, no filler. The primary action and its side effects come first, and the gating rule follows immediately after; every clause carries decision-relevant 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?

With 5 parameters at full schema coverage, an output schema for return values, and annotations covering the safety profile, the description supplies exactly the missing layer: side effects and the refusal/override rule. Nothing needed to call it correctly is absent.

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 the baseline is 3, but the description adds meaning beyond the schema by tying by=owner and reason together and stating that the reason is persisted in the new feature's lifecycle. The name/root/title parameters get no additional treatment, which keeps it from a 5.

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 ('Write the skeleton of a new spec-loop feature') and enumerates the concrete side effects: next FEAT number, first phase, render, refresh spec/README.md. This is clearly distinguishable from siblings like features (listing), phase (advancing), and render (regenerating output).

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?

Explicitly states the precondition and the refusal behavior ('refuses while another feature is not done, naming it') plus the override path via by=owner with a reason. It lacks explicit routing to siblings such as features/status for checking whether an in-progress feature blocks creation, but the when/when-not guidance is clear.

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