op3_verify_prefix

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

Annotations already provide readOnly, idempotent, and non-destructive hints, so the bar is lower. The description adds valuable diagnostic behavior: it separates three externally identical failure cases and can say what is wrong. This goes beyond what the annotations alone convey.

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 front-loaded with the core purpose, follows with a clear trigger for use, and then explains the key diagnostic nuance. Every sentence contributes; there is no filler or redundancy.

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 diagnostic tool with no output schema, the description sufficiently explains what the tool does, when to run it, what kinds of outcomes it distinguishes, and which input is most useful. An agent has enough context to select and 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?

Schema description coverage is 100%, so the parameters are already documented. The description adds extra meaning by explicitly advising that a feed URL is the most useful input because the typical failure is that OP3 has never seen that feed. This guidance supplements the schema.

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: 'Check whether OP3 is actually receiving downloads for a show' and clearly identifies the resource. It also distinguishes this diagnostic tool from the many lookup/download siblings by explaining it is the first tool to run when numbers are zero or a show cannot be found.

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 usage context: 'Run this first whenever the numbers are zero or a show cannot be found.' This is a clear trigger condition that guides tool selection, though it does not explicitly name alternatives or state when not to use it.

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