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

The description adds significant behavioral context beyond annotations: it explains the whole-body replacement semantics ('to append, read the current text first'), the required OAuth authentication, and the return of the updated note. It complements the annotations (readOnlyHint=false, idempotentHint=true) without contradiction, giving the agent essential execution details.

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 concise sentences, each earning its place: purpose and note id source, behavioral replacement note, and routing/alternative plus auth and return. Front-loaded with the core action, no redundancy, and perfectly structured for quick comprehension.

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?

The description is complete for an agent to call this tool correctly: it covers the action, the source of the identifier, the replacement semantics to avoid data loss, the alternative tool, the authentication requirement, and the return value. With full schema coverage and this description, an agent has all necessary information.

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?

The schema already covers all parameters with 100% description coverage, so the baseline is 3. The description adds value by clarifying that 'body' is the full new text (reinforcing the replacement behavior), and that 'date' is for moving the note (matching the schema). It also notes the source of noteId, which is not in the schema. This slightly elevates it above baseline.

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 clearly states the tool replaces a day note's text and/or moves it to another day, using the note's id. It distinguishes itself from journal_update_trade by explicitly naming the alternative for trade notes, making its purpose unambiguous and easily differentiable from siblings.

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 explicitly specifies when to use this tool (updating existing day notes) and when not to (trade notes via journal_update_trade). It also indicates the source of the note id (from journal_get_day or journal_search_notes), providing clear selection and exclusion criteria.

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