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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the write/replace profile is covered. The description adds genuinely new behavior beyond that: it discloses the key-validation gate and the rejection path ("any other key is refused"), which an agent could not infer from the annotations. It stops short of saying whether existing values are overwritten and whether values are stored as secrets.

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, with the core action first and the acceptance constraint immediately after. No filler, no restatement of the title.

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 three-parameter mutation tool with annotations covering the safety profile and no output schema, the description is workable but leaves gaps: the effect on an already-set key, the nature of the stored value, and any resulting state are all unstated. An agent knows the validation rule but not the full consequences of a successful call.

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 only 33%: key is documented in the schema, while value and appId carry no prose. The description does reinforce the key constraint (detected-in-source), but adds nothing about what value represents (plaintext vs secret, max size, encoding) or about appId. Partial compensation for a low-coverage schema, so a mid score.

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?

"Saves a configuration value for an app" gives a specific verb (saves) and resource (configuration value) with the scope narrowed to a single app. It is clearly distinguishable from siblings like deploy, get_logs, get_status and list_apps, though it never explicitly contrasts itself with them.

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 states a precondition for use (the key must be one Utplava detected as needed in the app's source code), which implicitly tells the agent when the call will succeed. However, it never frames this as when-to-use guidance, names no alternative tool, and says nothing about which situations call for setting a value at all.

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