Create a journal entry

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

Annotations already convey that this is not read-only, not idempotent, and not destructive. The description adds a meaningful behavioral constraint: only calendars that accept journal entries can be used, and list_calendars is the way to identify them. It does not contradict any annotation.

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?

Two short sentences with no filler. The primary action is front-loaded, and the second sentence provides essential routing guidance without repeating schema or annotation 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?

Given a fully documented input schema, an output schema, and explicit guidance about which calendars support journal entries, the description is complete enough for an agent to call the tool correctly. Nothing needed for selection or invocation is missing.

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%, and the schema richly documents all six parameters including calendar_id, date, summary, timezone, categories, and description. The tool description adds no parameter-level meaning beyond referring to a 'dated note', so the baseline 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 uses a specific verb ('adds') and names a distinct resource ('a dated note' / journal entry) rather than repeating the tool title. It also restricts the operation to calendars that accept journal entries, which clearly separates it from calendar/event tools like create_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?

It tells the agent how to find an appropriate target by pointing to list_calendars ('list_calendars reports which do'). It does not explicitly name alternatives like update_journal or create_event, but the journal-specific wording provides enough context for typical use.

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