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

With no annotations, the description carries the full burden. It discloses the digest's components, how restated values are listed separately, that empty days are reported with a reason and never padded, and that 'nothing moved' when the date hasn't advanced. This is rich behavioral context, though it does not cover return format or rate limits.

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 tightly structured: purpose first, a scannable list of contents, then usage guidance. Every sentence earns its place with no redundant or filler wording.

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?

For a zero-parameter tool with no annotations or output schema, the description fully explains what the digest contains, when to call it, and how empty days are handled. The 'Try: {}' example confirms invocation, leaving no significant gaps for an agent.

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 tool has zero parameters and an empty schema, so there is nothing to explain. The description adds a 'Try: {}' invocation example, which is the only meaningful addition. Baseline for 0 parameters is 4.

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 'Get the daily what-changed digest for the newest data day' and enumerates its contents (new readings, restated values, projections, Market Wire editions), making the tool's purpose explicit and distinguishing it from the more specific sibling get_* tools.

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 explicitly frames itself as 'the first call of an agent's day' and explains the 'if date hasn't advanced since your last look, nothing moved' check, providing clear when-to-use context. It does not name alternatives or when-not scenarios, but the digest role makes its usage intent obvious.

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