Mood timeline

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

Annotations cover only readOnlyHint and openWorldHint, so the description carries the burden of describing output shape, which it does well: the aggregation fields and the rising/falling/steady trend are disclosed up front, and the explicit exclusion of journal text is a meaningful privacy signal. It stops short of stating anything about the 366-day window or behavior on empty ranges, but the schema covers the range limit.

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?

One compact sentence front-loads the resource and scope, then lists return fields in a scannable order, closing with the exclusion. No filler or 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?

There is no output schema, so the description must describe return values — and it does so field by field, including the derived trend signal. Combined with the schema's date-range constraints and defaults, an agent has everything needed to call this correctly.

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 67%: from and to are fully documented with defaults and the 366-day limit, while bucket has only an enum and default. The description's 'grouped by day or week' explains what the bucket choice produces, but that largely restates the enum values rather than adding new meaning.

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 names a specific resource (mood) with a specific scope (date range, bucketed by day or week) and enumerates exactly what is returned: entry counts, average valence/arousal, top emotion labels, and trend direction. The closing 'No journal text' draws a hard line against text-fetching siblings such as get_entry_text.

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?

'No journal text' implicitly routes text-seeking requests elsewhere, but no sibling is named and there is no explicit statement of when to prefer this over list_entries or get_entry_text. Usage is inferable rather than stated.

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