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

Annotations already declare readOnly and idempotent behavior, and the description reinforces this without contradiction. It adds valuable behavioral context beyond annotations: 'requires no API key', 'rate-limited', and the returned shape ('per-resolver values and a consistency verdict'). This goes beyond the structured fields.

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 appropriately sized with every sentence contributing: purpose, usage, alternative, constraints, and return summary. It is front-loaded with the core action and outcome, and the guidance about dns_lookup is placed clearly without excess verbiage.

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?

For a two-parameter, read-only tool with an output schema and comprehensive annotations, the description is complete. It covers use case, alternative routing, rate limiting, authentication requirements, and return verdicts, so an agent has everything needed to invoke it 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?

Input schema coverage is 100%, so the schema already fully documents both parameters. The description adds general context about comparing records but does not add meaning beyond what the schema provides. This is the correct baseline for high schema coverage.

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 uses a specific verb ('Query') with a clear resource ('one DNS record across 8+ global public resolvers') and a concrete outcome ('report which resolvers return stale versus updated values'). It clearly differentiates from the sibling dns_lookup tool by focusing on multi-resolver propagation rather than a single authoritative answer.

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 explicitly states when to use it ('after changing a record to confirm worldwide propagation') and names the alternative tool with the condition for choosing it ('Use dns_lookup instead for a single authoritative answer with SPF/DMARC validation'). This leaves no ambiguity about selection.

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