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

Annotations cover the read-only/idempotent/closed-world profile, and the description adds substantial extra context they don't convey: per-item billing against allowance or credits, per-item receipts, the 50-item cap, and the organization-key auth requirement. These are exactly the operational facts an agent needs before invoking.

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?

Three tight sentences, zero filler, with the batch scope and cap front-loaded before secondary details like billing and auth. Every sentence earns its place.

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?

Covers the operational essentials (cap, billing, auth) for a batch-check tool and the schema fully documents the input shape. With no output schema, it could optionally say what each check returns beyond 'receipt,' but nothing critical for correct invocation is missing.

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 description coverage is 100%: the items array format (text, direction, source) is fully documented in the schema itself. The description adds no syntax or format detail beyond that, and the per-item billing note is behavioral rather than parameter semantics, 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 and resource with explicit batch scope: 'Check up to 50 texts in one call.' The batch framing clearly separates it from the singular guard_check sibling, though it never names that sibling explicitly, so it falls short of full sibling differentiation.

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?

Gives a concrete usage context ('for example every tool result in a step'), which tells the agent when this tool fits. It does not, however, state when to prefer the single-check sibling guard_check or any exclusions, so no explicit alternative routing.

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