set_env

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 env vars are set/replaced, that a rolling restart occurs without rebuild, that values are never echoed back, and that build-time vars are deferred until the next deploy. These are exactly the non-obvious behaviors an agent needs to know.

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?

Three sentences with no filler. The core action and restart behavior are front-loaded, followed by the security caveat about echoing and the build-time deploy timing note. Every sentence earns its place.

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 mutation tool with no annotations and no output schema, this description covers the most decision-relevant behavior: restart mechanics, rebuild implications, echo behavior, and deploy timing. It does not explicitly state what happens to omitted env keys or how success/failure is reported, but it is sufficient for correct invocation.

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?

The input schema already describes both parameters fully (100% coverage), so the baseline is 3. The description adds behavioral caveats but no additional parameter-level syntax or value-format information 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 uses a specific verb and resource ('Set/replace a container's environment variables') and immediately differentiates itself with 'rolling restart, no rebuild'. This makes the tool's purpose and scope unmistakable, even alongside deploy-related siblings.

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 provides clear operational context: changes are applied via rolling restart without rebuild, and public build-time variables only affect the bundle after the next deploy. This implies when to prefer deploy for build-time vars, though it does not explicitly name the sibling tool.

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