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

Annotations already declare non-readOnly, destructive and idempotent behavior, so the bar is lower; the description still adds the key trait that the call overwrites existing values for the supplied fields, and constrains the edit surface to a fixed field list. It does not cover permissions, error behavior on invalid ids, or whether omitted fields are preserved outside the 'only these fields' clause.

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?

Front-loaded with the action and lookup key in the first clause, then the field list. Two sentences, no filler; the backtick field enumeration is dense but each token earns its place by preventing invalid keys.

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 mutation tool with no output schema, the description covers what is mutated, which fields are legal, and that values are overwritten. Missing only edge details such as invalid-id handling and `changes` value formats, which are minor against annotations that already declare the destructive/idempotent profile.

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 `changes` is a free-form object with additionalProperties=true, so the description carries the burden; it enumerates the seven whitelisted keys (ts, ml, foods, note, meal_type, kind, author) and states they are the only editable ones. It stops short of explaining value formats (timestamp encoding, ml units, foods structure), but the field whitelist is the critical semantic the schema lacks.

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 ('Edit') and resource ('a previously logged event'), pins the lookup key ('by its id'), and even names where to obtain that id (get_events/get_today). This distinguishes it cleanly from the log_* creation siblings and from delete_event.

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 description usefully routes the agent to get_events/get_today to obtain the id, which is real usage context. However, it offers no explicit when-to-use versus delete_event or undo_last, and no exclusion/precondition guidance, so usage remains 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.