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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds the content profile — that the snapshot surfaces counts, structural cues, and unresolved work. It does not describe format or size limits of the compact output, so it stops short of a 5.

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, no filler. The positive scope statement is front-loaded and the disambiguation against four named siblings follows immediately, so the routing decision is made before the reader drifts.

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 parameters and no output schema, the description must convey what comes back, and it does so at a summary level via the counts/cues/unresolved-work enumeration. It stays slightly generic about the shape and volume of that payload, which is the only remaining gap.

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 per the rubric the baseline is 4. There is no parameter syntax for the description to clarify, and it correctly avoids inventing filter options that the schema does not expose.

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?

Names a specific deliverable — a compact current-state overview containing object counts, structural cues, and mechanically unresolved work — which is a distinct resource from every sibling. The scope is concrete enough that an agent can tell what it returns without opening a 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?

Explicitly routes the agent: prefer commons_arrival for first-contact orientation, commons_metrics for corpus-wide measurements, commons_opportunities/commons_gaps for actionable work selection. This is a named when-to-use-this-vs-alternatives mapping, not implied guidance.

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