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

No annotations are provided, so the description carries the full burden. It does not disclose whether the result is cached, how stale it can be, whether the 'latest' scan is immutable, whether calling has side effects, or what the return structure looks like. For a tool with zero annotation coverage this is a notable gap.

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 that states the action, the source, and the payload without waste. It is appropriately sized for a simple reporting tool, though the colon-clause is slightly dense.

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?

Given one optional parameter, no output schema, and no annotations, the description is adequate but not complete. It does not describe the response shape (counts, deltas, server lists) or freshness, leaving the agent to infer the return contract.

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 the schema fully documents the single 'days' parameter (window in days, default 7). The description does not elaborate on the parameter (e.g., whether it controls the comparison baseline or the scan lookback), so it adds no value beyond the schema; baseline 3 applies.

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 states a specific verb and resource ('Return the latest weekly scan of the official MCP registry') and clarifies the content: directory health check pass count and week-over-week changes. No siblings exist, so no differentiation is required, but the purpose is unambiguous.

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 implied by the nature of the tool — an agent would call it to retrieve current registry scan results — but there is no explicit when-to-use guidance, no alternatives (none exist here), and no indication of frequency limits or freshness constraints.

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