update_journal_entry

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

With no annotations provided, the description must disclose behavioral traits. It reveals that the tool finds by time, uses existing_headline to disambiguate, and replaces content/tags (e.g., 'Updated tags (replaces existing)'). It also points to a format guide for further specs. While it doesn't detail side effects like whether other fields are overwritten, the disambiguation and replacement behavior is genuinely informative.

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 compact: three sentences that state what it does, how it finds the entry, and when to use it. The disambiguation note is front-loaded and the format pointer is a useful addition without bloat.

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 no annotations and no output schema, the description handles the essential behavior (lookup, disambiguation, replacement) and routes to a format guide. It doesn't state what the return value is or whether the update is destructive to unspecified fields, but it covers the core operation thoroughly.

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 schema already documents all parameters. The description adds meaning by explaining the lookup mechanism (time + existing_headline) and clarifying that tags replace existing, which is valuable. However, it doesn't explain the relationship between time/existing_time fully beyond the schema defaults, but the schema description covers most.

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 explicitly states the verb ('Update'), the resource ('existing journal entry'), and the mechanism (find by time, with existing_headline for disambiguation). It distinguishes itself from create_journal_entry and search_journal by focusing on updating existing entries and adding details, which is clear from the sibling list.

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 includes explicit guidance on when to use this tool: 'Use this to correct or enhance existing entries, or add forgotten details like task links.' It also implicitly excludes creation by saying 'existing journal entry' and provides a disambiguation strategy. However, it does not explicitly mention alternatives like create_journal_entry, but the use-case guidance is strong enough to route the agent correctly.

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