parse_email_headers

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

Annotations already indicate readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds that the tool is offline and requires no API key, which is valuable beyond the annotations. No contradictions.

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?

Two sentences: the first defines action and outputs, the second provides usage guidance. No redundant information; every sentence serves a purpose.

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 tool has a simple interface with one required parameter and an output schema (implied). The description covers the key analyses performed and even suggests a related tool (check_ip). All essential information is provided.

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 provides detailed descriptions for both parameters (raw_headers and response_format), so schema coverage is 100%. The description does not add parameter-level details beyond the schema, but the context about offline usage is general.

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 analyzes raw email headers for spoofing, specifying SPF/DKIM/DMARC results, header mismatches (From vs Return-Path vs Reply-To), and the originating IP. This distinguishes it from sibling tools like check_email or check_domain_auth.

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?

It explicitly says 'Use when: the user can paste the full raw headers of a suspicious email,' providing clear context. It does not explicitly state when not to use or list alternatives, but the usage guidance is direct and helpful.

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