parse_dmarc_report

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

The description discloses key traits beyond annotations: the tool is stateless ('nothing is stored, parsed and discarded'), idempotent, and read-only (matching annotations). It also specifies input size limits (2 MiB decoded) and format support, which annotations do not cover, adding significant behavioral context.

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 three sentences, each earning its place: purpose, required input format, and stateless nature. It is front-loaded with the core action and efficiently conveys all necessary details without redundancy.

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?

The description adequately covers input, constraints, and effect. It hints at output ('readable per-source aggregates') but does not detail the exact structure. Given no output schema, a brief mention of the output format would improve completeness, but the core information is sufficient for correct invocation.

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 description adds meaningful context beyond the input schema. For 'content_base64', it clarifies to encode file bytes, not paste raw XML. For 'filename', it notes the filename is only for logging and does not affect parsing. This helps the agent avoid common mistakes.

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 parses a single DMARC aggregate (RUA) report into per-source aggregates, specifying what information is extracted (sender, volume, SPF/DKIM alignment). This is distinct from sibling tools which handle building, checking, or generating DNS records, so 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?

The description provides explicit instructions on how to invoke the tool: pass base64-encoded file bytes, optionally with a filename. It states the file can be XML, .gz, or .zip up to 2 MiB. While it does not contrast with siblings, the context of parsing vs. fetching (get_report) or checking DNS records is clear enough for an agent to decide.

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