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

Goes well beyond the readOnlyHint=false / destructiveHint=false annotations: it discloses encryption at rest, boot-time injection, that values are never returned, that the default behavior restarts the running server, and that the operation is free. These are exactly the side effects an agent needs before invoking a mutation.

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?

Dense but front-loaded: what it stores, why it is safe, the alternative it replaces, then the side-effect/cost caveat. No sentence is filler and the apply:false nuance is handled in a short parenthetical.

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 output schema and reasonable annotation coverage, it supplies the safety profile, default side effect, and cost. It omits authorization/permission requirements and whether unset also triggers a restart, which are the remaining gaps an agent might need.

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 already 80% and documents apply, unset, and service. The description reinforces the apply semantics ('next deploy uses them') but says nothing about unset (secret removal) or service selection, so it adds only marginal meaning over the structured fields.

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 (store write-only secrets for a server) and immediately characterizes the payload (API keys, DATABASE_URL). The phrase 'use this, not env, for credentials' actively separates it from the env-related siblings (env_link, set_build_vars). An agent can identify the tool without opening the 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?

Gives a clear when-to-use rule ('for credentials') plus an explicit not-condition ('not env'), and explains the apply:false branch as the store-only path. It stops short of naming the actual sibling tool that handles non-secret env vars, so the routing is directional rather than exhaustive.

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