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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, so the safety profile is known. The description adds genuinely new behavior: unauthorized fields are refused by name with 400 UNKNOWN_FIELD and nothing is persisted, and the required permission 'Update your profile' (profile:write) is named. It does not discuss idempotency or repeated-call behavior, which is the remaining gap.

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 action and its scope constraint are front-loaded, and the sentence order moves from what changes to what is refused to what authorization is needed. It is fairly dense and the closing line about member-authored text reads as boilerplate, but almost every clause carries operative information.

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?

There is no output schema, and the description compensates by stating that the call answers with the section read back. Combined with the mutation scope, refusal semantics, and permission requirement, an agent has everything needed to call this correctly, including the not-yet-connected sign-in path.

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% and both fields carry descriptions, so the baseline is 3. The description reinforces that 'level' is the sole mutable attribute and that surrogate fields such as target_user_id are rejected rather than silently ignored, but it adds no syntax or format detail beyond 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?

It states a specific verb and resource ('Correct a language') and immediately narrows the scope: only the 'level' field is mutable, not the language itself. That scope distinction separates it from add_my_language and remove_my_language, which are the obvious siblings, without needing to open 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?

It gives an explicit alternative for the out-of-scope case ('to change the language itself, remove it and add the right one'), and it names which fields are rejected with which error code. Both when-to-use and when-not-to-use are covered, plus the routing to the correct sibling pair.

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