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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the description only needs to add context. It contributes a genuinely non-obvious trait not present in the annotations: this call is free and produces a limited preview rather than a full paid artifact, which matters for an agent deciding whether to spend a call.

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?

A single sentence that front-loads the key differentiator ("FREE, no payment") and then lists the concrete checks. No padding, though the commercial framing ("before buying a full evidence receipt") is more marketing than operational.

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 read-only, no-output-schema tool, the description tells the agent what the call returns at a high level (reachability, protocol negotiation, tool count, schema issue count), effectively covering the missing output schema. Auth requirements and rate limits are unstated but are not critical for a preflight call.

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?

Schema coverage is 100%, so the schema already documents target_url, check_profile, and declared_protocol_version. The description's enumeration of checks (reachability, protocol negotiation, tool count, schemas) largely restates the schema's own description of the "basic" profile, adding little beyond it, so the baseline 3 applies.

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?

States a specific verb (run a verification/compatibility preflight) against a specific resource (an MCP server endpoint) and enumerates what it checks: reachability, protocol negotiation, tool count, schema issue count. It is clearly distinguishable from heavy siblings like mcp_release_certify, though it never names that sibling explicitly.

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?

"before buying a full evidence receipt" and the schema note "before deployment or integration" give a clear condition for using this instead of the paid path. However, the alternative is referred to only obliquely (no tool name like mcp_release_certify), so the routing is implied rather than explicit.

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