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

Annotations already declare destructiveHint=true, idempotentHint=false, and readOnlyHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond the annotations: env and secret_env replace the whole map (not merge), and changes only affect processes started afterward. It does not mention auth/permission requirements, keeping it from a 5.

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 tight sentences, front-loaded with what is updated and then the two highest-risk behavioral facts (replace semantics, propagation timing). No filler.

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 5-parameter mutation tool with nested objects, no output schema, and annotations covering safety, the description supplies the critical replace-semantics and timing details. It omits permission requirements and behavior of omitted fields (e.g. whether cwd is unchanged when not passed), so it is not fully complete.

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 semantics the schema does not: env and secret_env are whole-map replacements rather than merges, and the update is scoped to future processes. cwd and the ID parameters are left to the schema.

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 (updates) and resource (a machine's execution defaults) and enumerates the affected fields (cwd, env, secret_env). It is clear enough to distinguish from machines_create/delete/get/list, though it does not explicitly name or contrast those 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?

There is no guidance on when to use this tool versus alternatives, nor any prerequisites (required orgID/machineID, permission or grant requirements). The sentence about changes applying to later processes is behavioral, not usage-routing guidance.

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