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

Annotations already establish this as a read-only, idempotent, non-destructive, closed-world call, so the safety profile needs no restating. The description adds value by disclosing the metric categories returned — important since there is no output schema — but does not clarify whether these are counts or embedded records.

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?

A single compact sentence that leads with scope ('What this deployment holds') and then enumerates the metrics. No filler, nothing redundant.

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 and no parameters, the description carries the full burden of describing the return value, and it only partially does so — it lists subjects but not whether each is a count, a list, or a nested object. Adequate to select the tool, thin for predicting its output shape.

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 takes zero parameters, so there is nothing for the description to disambiguate; baseline is 4. No parameter guidance is needed or expected here.

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 exactly what the tool reports (collections, sources, items, items added today, feeds), which is far more specific than the bare name 'stats'. It implicitly distinguishes itself from list_* siblings by returning a summary of holdings rather than records, though it never says 'counts' or names a sibling.

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?

Usage is only implied: an agent can infer this is the overview/summary call for the deployment. There is no explicit when-to-use statement and no routing away from alternatives such as list_collections, list_sources, or population, which overlap in subject matter.

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