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

With annotations only covering the read/write and world flags, the description carries real behavioral weight: a ~2-minute duplicate check with the exact reply text, undoability from the record, 'Added by <this app>' attribution, the returned id name, cost ($0.10), and the API-key requirement. This is well beyond what the annotations disclose and consistent with readOnlyHint=false.

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 verb, and the dense single paragraph earns most of its length through routing, idempotency, and cost details. It does re-enumerate the enum values (food/meal/snack/drink/kopi/coffee) already present in the schema, a minor redundancy.

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 10-parameter write tool with an output schema, it covers everything an agent needs: routing, idempotency/retry semantics, cost and auth requirements, undo path, and the returned id. Little is left to inference.

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 baseline is 3, but the description adds cross-parameter meaning the schema does not: for food types a Finance row is created 'when amount is given', linking the optional amount to a side effect, and it frames text as the user's own words. It adds value without restating every field.

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 ('CREATES one entry') and precisely maps each type value to its destination (Food Diary, Finance, private Moment), which tells the agent exactly what gets produced. It does not, however, explicitly differentiate itself from the sibling log_food / log_expense / log_moment tools, which an agent could easily confuse it 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?

The type→destination routing implies when each branch applies ('type food... → Food Diary'), giving usable context. But there is no explicit when-to-use statement, no conditions or exclusions, and no naming of the closest alternatives (log_food, log_expense, log_moment) despite them existing as siblings.

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