sigma_rule_lookup

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds beyond that by detailing the return fields (title, description, status, level, logsource, detection logic, tags, etc.) and rate limits (30/hr free, 500/hr Pro). It also notes the refresh cadence (daily at 02:00 UTC) and the next_calls behavior. No contradictions with annotations.

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 a single paragraph that efficiently packs all essential information: purpose, return fields, usage context, rate limits, and follow-up suggestions. It is not overly verbose but could be slightly better structured with bullet points or separation of concerns. Still, every sentence adds value.

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 the tool's simplicity (one parameter, clear output schema mentioned), the description is complete. It covers what the tool does, what it returns, rate limits, and even hints at follow-up tools. No missing information for an agent to invoke correctly.

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% (the single parameter rule_id has a description with example and source). The tool description does not add significant additional meaning beyond the schema. Baseline 3 is appropriate as the schema already does the heavy lifting.

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 the tool's purpose: 'Look up a single Sigma detection rule by UUID from the SigmaHQ corpus'. It specifies the resource (Sigma rule), the verb (look up), the identifier (UUID), and the source (SigmaHQ corpus). It differentiates itself from the sibling sigma_rule_search by mentioning that it is used to fetch a known rule or inspect a rule discovered via search.

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 provides clear usage guidance: 'Use to fetch a known rule for context (e.g., a SIEM detection that fired) or to inspect a rule discovered via REST sigma_rule_search.' It also hints at when follow-up tools are relevant via next_calls. However, it does not explicitly state when not to use this tool or list alternatives, so it falls short of a 5.

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