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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds a genuine behavioral detail beyond the annotations: the call is 'Free' (no credit cost). Beyond that it largely restates what the output schema already carries (counts and verification info), so it does not go much further.

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 front-loaded sentence with no filler; the counted dimensions come first and the cost note last. Slightly run-on phrasing ('and how to verify the evidence') keeps it from being maximally tight.

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, read-only stats tool with annotations and an output schema, the description says enough to know what is returned. The only gap is routing guidance among the numerous scan_* siblings, which the description does not address.

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 clarify beyond the schema. Baseline 4 applies for a parameterless tool.

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 and what is counted: MCP servers tracked by status and grade, tools indexed, changes recorded. An agent can tell this is an aggregate/statistics read rather than a search or listing. It does not explicitly contrast with siblings like scan_changes or scan_search, so it stays below 5.

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?

There is no statement of when to call this versus the many sibling scan_* tools (scan_search, scan_changes, scan_owner_listing). The word 'Free' hints at cost but is not framed as a usage condition. The agent must infer the use case from the purpose alone.

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