journal_get

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

Beyond the readOnlyHint annotation, the description reveals a non-obvious rule: trend direction is only named with at least five days of check-ins and a 0.5 difference, and otherwise mood_trend.reason explains the null. This prevents an agent from misreading a null trend as 'no change,' which is exactly the kind of hidden behavior that matters.

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 first sentence is a clear front-loaded statement of function, and the second adds a necessary qualification about trend naming. Both sentences earn their place, and the prose is compact for the behavioral nuance it conveys.

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?

With no output schema, the description names the major return components (mood check-ins, gratitude entries, mood trend) and explains mood_trend's null behavior, so an agent understands what it will receive. It does not describe entry-level fields or ordering, but those are less critical for correct invocation given the simple optional parameter.

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 only parameter, days, has no schema description and the description does not explicitly explain it, though 'recent' hints at the lookback window. The schema's type, name, and default make the parameter fairly self-evident, so the lack of additional detail is not severely penalized.

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 opens with a specific verb and resource: 'Return recent mood check-ins, gratitude entries, and mood trend.' This clearly identifies what the tool retrieves and distinguishes it from the record-creation siblings like mood_record and gratitude_record.

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 implies the tool is for retrieving recent journal/mood data, but it does not explicitly state when to use it over alternatives such as mood_record or gratitude_record. Usage must be inferred from the tool's name and domain rather than from direct guidance.

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