PeerGlass

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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds valuable context about the data source ('RIPE NCC's Passive DNS system, which aggregates DNS queries from recursive resolvers') and return format specifics ('first/last seen timestamps and observation counts') that clarify what 'historical' means in practice.

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?

Description is well-structured with distinct sections (main purpose, useful for, data source, args, returns) and no wasted text. Every sentence provides unique value—whether describing the external data source, enumerating use cases, or documenting parameters.

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 has an output schema and annotations covering safety hints, the description provides comprehensive coverage: it explains the external data source, return value structure ('Historical DNS records table with rrtype, value, and first/last seen dates'), and fully documents all parameters despite zero schema coverage. Complete for a historical lookup tool.

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?

With 0% schema description coverage (per context signals), the description fully compensates by documenting all three nested parameters under 'Args': resource (IP or domain), limit (default 100, max 500), and response_format (markdown/json options). This provides complete semantic meaning absent from the structured schema.

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?

Description explicitly states the tool 'Query RIPE Stat Passive DNS for historical DNS records' specifying the verb (Query), data source (RIPE Stat), resource type (historical DNS records), and targets (IP or domain). This clearly distinguishes it from active DNS resolution siblings like peerglass_dns_resolve.

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 'Useful for:' section provides four specific scenarios (tracing infrastructure changes, finding previously-used domains, investigating C2 infrastructure, threat hunting) giving clear context for when to use the tool. However, it does not explicitly name alternatives (e.g., peerglass_dns_resolve for current DNS) or exclusion criteria.

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