set_user_option

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

Annotations already declare the write/destructive/non-idempotent profile; the description adds genuine value beyond them with the key allowlist, namespace prepending (explaining cross-user/global isolation), the 400 failure mode, and the note that JSON-encoded string fields must stay strings. It stops short of describing overwrite semantics or what success returns, which is the main gap for a destructiveHint=true tool.

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?

Four compact sentences, front-loaded with purpose, then semantics, error behavior and encoding caveat. No redundant restatement of the name or schema, and every sentence carries actionable 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?

For a single-parameter mutation with no output schema and rich annotations, the description supplies scoping, validation and encoding rules that make correct invocation possible. The missing pieces are overwrite semantics and confirmation of what a successful store returns.

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%, so the description must carry the load, and it does: the `key` is defined as an allowlisted suffix that the server namespaces, and the value is constrained to string type (including JSON-encoded strings). It still doesn't say whether `key` and `value` are both required or what the value's size/content limits are, so it isn't exhaustive.

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+resource+scope: 'Stores one option for the authenticated user', plus the transport hint 'POST /user/options'. It implicitly separates itself from server-wide option writing by noting a request can never touch a global option, though it doesn't explicitly name set_server_option or get_user_options.

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?

Clear context for use: only allowlisted key suffixes are accepted, unknown keys return 400, and the server namespaces per user. It does not explicitly route the agent to alternatives (e.g. set_server_option for globals, get_user_options for reads), so usage is implied rather than fully specified.

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