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

Annotations already declare readOnlyHint=false and destructiveHint=false. The description adds material context the annotations cannot: values are stored and returned in plain text, and the write only affects the project default, not tenant overrides. It does not cover return payload or idempotency semantics, but the behavioral picture is strong.

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 tight sentences, front-loaded with the core action, followed by the set_secret routing and the scope caveat. No filler, though the third sentence is somewhat dense. Every sentence contributes.

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 4-param mutation with no output schema, the description supplies the security posture, the alternative tool, and the default-vs-override scope. An agent has enough to call it correctly; only return/response behavior is unspecified, which is moot given no output schema.

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 schema already documents all four parameters (including the AWS_/AALY_ naming restriction). The description references req.env['KEY'] reading syntax, adding slight meaning, but largely the schema carries this dimension. Baseline 3 is correct.

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 (Set) plus resource (NON-SECRET configuration value) and even gives the runtime access path req.env['KEY']. It directly distinguishes itself from the sibling set_secret by naming the boundary between the two.

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?

Explicitly says when NOT to use it: anything unreadable like an API key or OAuth token belongs in set_secret instead. It also clarifies scope (this sets the project default; tenant overrides are not reachable here), which prevents misuse.

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