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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is largely covered. The description adds genuinely non-obvious behavioral context the annotations cannot express: that re-calling the original tool creates a duplicate approval. It omits any hint about the return values/status vocabulary, which keeps it from a 5.

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 short sentences, zero filler, and the core action plus the critical 'don't re-call the original tool' warning are front-loaded. Every sentence carries distinct information.

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 one-parameter read-only tool with full annotation coverage, this is nearly complete: it says what it does, how to call it, and the pitfall to avoid. With no output schema present, it could have sketched what status values come back, which is the one remaining gap.

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% and the single parameter is already documented as 'REF number returned from a prior tool call that required approval.' The description repeats the same REF concept without adding format, source, or validation detail, so the schema does the heavy lifting.

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 ('Check the status of a pending approval request') plus the lookup key ('by REF number'), which implicitly separates it from the bulk-oriented list_pending_approvals. It stops short of naming that sibling explicitly, so differentiation is inferable rather than stated.

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?

Explicitly names the situation for use ('between retries of a tool call that is pending approval') and an explicit prohibition with its consequence ('Do NOT call the original tool again... that will create a duplicate approval'). Both the when and the when-not are covered.

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