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

Annotations already declare non-read-only, non-destructive, non-idempotent, and closed-world behavior. The description adds substantial context beyond annotations: it copies the lambda's files, documentation, tests, and data; creates a separate preview address; and leaves the live version serving visitors throughout.

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 purpose is front-loaded in the first clause, and the remaining sentences explain the workflow and safety guarantee without filler. Despite being dense, every sentence contributes useful context for a multi-step feature workflow.

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 covers the creation behavior, isolation guarantee, and subsequent lifecycle steps well. With no output schema, it would be stronger if it explicitly stated what create_feature returns, such as the feature identifier or preview address needed by later calls.

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 meaning of base, name, privateKey, and specification is already fully documented. The description aligns with those definitions but does not add syntax, constraints, or semantics beyond what the schema provides.

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 verb and resource: starting a feature that branches from a version, copies files and data, and gives a preview address. It clearly distinguishes this from changing a live lambda and names related tools such as change_code, write_code, deploy, and merge_feature.

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?

It gives strong contextual guidance: use this to change a lambda without affecting what is online, then use change_code/write_code, test the preview, and merge when ready. However, it does not explicitly contrast this with directly updating the live lambda via update_lambda or update_feature, so it is clear without full when-not routing.

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