user_checkauthentication

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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real value beyond that by disclosing the auth prerequisite (a session id, not server credentials) and that a successful check returns the user's details, which the annotations do not convey.

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 short sentences, front-loaded with the core purpose and return value, followed by the prerequisite. Efficient and free of padding, though the RST double-backtick formatting is slightly noisy.

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 not be explained, and annotations cover the read-only nature. The description supplies the key prerequisite and credential caveat, leaving little an agent needs missing for correct invocation.

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 sessionid-vs-auth_sessionid distinction and the raw_json warning. The description reinforces that auth_sessionid validates exactly that session, but adds little syntax or format detail beyond the schema, making the baseline 3 appropriate.

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 ('Check whether a session is still valid') and adds the return behavior (authenticated user's details). It also implicitly separates itself from user.login by citing it as the source of the session id, though it does not name a sibling it must not be confused with.

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?

Gives clear context for use: auth_sessionid must come from a prior user.login, and it warns that configured server credentials (api_token or username/password) cannot validate against the session table. It lacks an explicit 'use this instead of X' routing statement, so it falls short of a 5.

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