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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered; the description adds useful scope detail that only one preference is affected and notes are untouched, confirming a low-blast-radius write. It stops short of mentioning idempotency or whether unsent/unchanged values are ignored.

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 compact sentences with no filler, front-loading the action and immediately bounding scope. The parenthetical value list is dense but earns its place by closing a schema gap.

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?

An output schema exists, so return values need no explanation, and for a one-key settings write the description covers purpose, scope, and valid values. Missing only auth/permission expectations and the exact parameter shape, which are modest gaps for a tool this narrow.

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 0% and the single parameter is a nested object ('set' containing 'dream'), so the description must carry the load. It supplies the permissible values (weekly, monthly, never) that the schema omits, but never explains the nested 'set.dream' shape, leaving the invocation path ambiguous.

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 ('Save the Cobrain settings') and narrows the scope to exactly one preference, the Dream cadence, with its allowed values. This cleanly separates it from the read-side sibling settings_read and from note-mutating tools like write_file or patch_file.

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?

Places the tool in a clear workflow context ('settings changed in ChatGPT's plugin settings page') and rules out note editing ('never touches notes'), which is real when-not guidance. It does not, however, explicitly name settings_read as the alternative for inspecting settings, so the routing is implied rather than stated.

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