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

Beyond the readOnlyHint annotation, the description adds valuable behavioral detail: no authentication key is needed, participants can have repeated names, returned start options are ranked by head-count, and only voteOptions usable by everyone with picks are returned. This meaningfully informs the agent about edge cases and response semantics that the schema and annotations do not provide.

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 description is front-loaded with the core action and then delivers a dense but purposeful list of returned fields. It is somewhat long and run-on, but every clause adds useful information and nothing is wasted.

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?

With no output schema present, the description carries the full responsibility of explaining return values, and it does so thoroughly: it names every major result group and notes the no-key requirement. For a single-parameter read tool, the agent has enough information to call it correctly and interpret the result.

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 100% for the single slug parameter, and the schema already explains its format and example. The description does not add parameter-level details, but it does not need to; the baseline of 3 applies.

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?

The description opens with a specific verb and resource, 'Read an event', and then enumerates exactly what data is returned: settings, startOptions, participants, ranked start times, voteOptions, votes, and decidedStart. This clearly distinguishes it from the mutating sibling tools like create_event, update_event, and vote_time.

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 'Read an event' framing plus the readOnlyHint annotation makes the retrieval purpose clear, and 'No key needed' tells the agent a key is not required before calling. It does not explicitly name alternatives or state when not to use it, but the context is unmistakable alongside the mutating siblings.

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