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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds a genuinely non-obvious behavioral trait: streak and best are computed only within the requested range, so a short range truncates a long streak. That nuance is not derivable from the annotations or schema.

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 sentences with no filler: the first front-loads the outputs, the second handles routing and the range/streak caveat. Every clause carries information an agent needs.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. The description still supplies the output inventory, the sibling routing rule, and the range/streak interaction, leaving nothing material missing for correct invocation.

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 baseline is 3. The description goes beyond the schema's terse 'window to cover' by explaining that the range bounds the streak/best calculations, giving semantic weight to the range parameter and concrete value guidance (90d, all). The field parameter, however, is left entirely to the schema.

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 enumerates the exact computed outputs (totals, today, daily average, streak, best day, goal progress) for a specific resource (a topic over a range), so the agent knows precisely what it returns rather than a generic 'summary'. It also explicitly contrasts itself with the sibling query_entries, making it distinguishable without opening either schema.

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 names the alternative (query_entries) and the exact query pattern that should route here ('how was my week'), then adds a concrete usage rule for the streak use case (pass 90d or all). Both when-to-use and how-to-use are explicit.

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