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

Annotations only supply readOnlyHint=true; the description carries the real behavioral load — no value passes through the agent or chat, public entries land as build settings while the rest become write-only secrets, the command shows names only and requires the user to click Allow in their browser. That is substantial context the annotations do not convey, and it is consistent with a tool whose own call only produces a link/command.

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 and the no-values-in-chat rule are front-loaded, and the follow-up clauses about command/url/next_step each carry actionable instruction. It is dense with semicolons and runs slightly long, but no sentence is 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?

With no output schema, the description correctly documents the three possible return shapes (command, url, next_step) and the browser-approval flow, which is the main thing an agent needs. It is incomplete on the input side — neither parameter's meaning nor any auth prerequisite is stated — which is the one real hole for a secret-handling tool.

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 0% for two input parameters, so the description must compensate and it does not: `projectId` and especially `service` (which has a pattern and 63-char limit) are never explained. The identifiers `command`, `url`, and `next_step` that it discusses are return values, not the declared inputs.

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 names a specific action and resource — delivering the USER's .env into the app — and explains the split of public entries into build settings versus write-only secrets. That mechanism cleanly separates it from siblings like set_build_vars and set_compute_secret, which an agent can see without opening any schema.

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 conditional handling for the result (run `command` in the user's project folder, else hand over `url` verbatim, else follow `next_step`) and a hard rule: never read a .env's values or ask for one in chat. It stops short of naming the alternative tools (set_build_vars / set_compute_secret) or stating prerequisites, so routing between siblings is left partly to inference.

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