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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses important behavioral nuances: rises are compared within the same EPSS model version so model releases never create false movers, and KEV status is included as observed-exploitation context. It also states the ordering (largest rise first), which is not derivable from annotations or the schema.

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 compact and front-loaded: the core purpose appears in the first clause, followed by parameter default, a key methodological caveat, output fields, and ordering. Every sentence contributes useful information; there is no filler or repetition of the tool name.

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 simple read-only tool with only two optional parameters and no output schema, the description is fully self-sufficient. It tells the agent what is returned, the ordering, the available windows and defaults, and why the mover signal is reliable, leaving no critical 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 input schema already fully describes both parameters, including the enum for window, the range for limit, and defaults. The description adds contextual meaning for window by explaining that it is the rise window, but it does not materially expand on limit or introduce semantics beyond the schema, so the baseline of 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 clearly states what the tool does: it returns CVEs whose EPSS exploitation probability rose most recently. It also lists the exact output fields (cve_id, current score, delta, KEV status and url), which is specific and unambiguous. However, it does not explicitly contrast itself with sibling tools like search_cves or get_updates, so the differentiation is implicit rather than stated.

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?

The description implies when to use the tool: when you want recent EPSS movers, and it explains the window choices (7d or 30d) and default. It does not explicitly state when not to use it or point to alternatives, leaving some routing inference to the agent.

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