discover

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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses that the tool performs DNS-only lookups (no HTTP), returns multiple TXT records each advertising a different server, and supports parallel batch lookup. This adds useful context beyond the schema, though it omits details like error handling or rate limits.

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, front-loaded with the core purpose ('DNS-only lookup'), and every sentence adds value—covering return payload, performance characteristics, and batch capability. No wasted words.

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 no output schema, the description adequately explains the return format (TXT records, potentially multiple). It covers the main use cases (single and batch), behavior, and performance. It lacks details on error scenarios or domain validation, but for a simple DNS lookup tool, the description provides sufficient context.

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 describes both parameters with 100% coverage, so the baseline is 3. The description adds only a minor clarification about single vs. batch lookup, which is already implied by the schema's parameter names and descriptions. No significant additional semantics are provided.

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 performs a DNS-only lookup of _mcp.{domain} TXT records, which is a specific verb+resource combination. It also distinguishes from sibling tools like discover_browse by emphasizing 'DNS-only' and 'no HTTP calls', setting it apart as a lightweight alternative.

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 usage through phrases like 'fast, cheap, no HTTP calls' and mentions support for batch lookup, but it does not explicitly name alternatives or provide when-not-to-use conditions. The context is clear but not fully explicit.

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