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

Annotations already establish read-only, idempotent, and non-destructive behavior. The description adds important behavioral context: this is a legacy, off-table resource that returns specific data, not the authoritative standard path. It does not cover errors or prerequisites, but the annotation burden is already substantially met.

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 compact, front-loads the legacy/off-table warning, then gives preferred tool routing and return contents. Every clause contributes, though phrases like OFF TABLE and x402 are domain jargon that could be clearer.

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 zero-parameter, read-only catalog with an output schema, the description provides the essential purpose, status, routing, and scope needed to decide whether and how to invoke it. Nothing critical is missing for making the 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?

The input schema has zero parameters and 100% schema description coverage, so there are no parameter semantics for the description to clarify. The baseline of 4 applies because no parameter compensation is needed.

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 identifies the tool as a legacy prepaid catalog and states exactly what it returns: credit bundles and x402 buy URLs for volume validates only. It explicitly excludes the authorize standard, so an agent can distinguish this from the broader SQLGuard flow.

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 gives explicit routing by saying to prefer sqlguard_handshake then sqlguard_challenge, and restricts use to volume validates only while excluding the authorize standard. The word prefer is slightly ambiguous about whether handshake and challenge are prerequisites or replacements, but the guidance is still usable.

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