Verify prefix

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuine behavioral value beyond that: it explains that the tool actively diagnoses and reports what is wrong, and enumerates the three distinct states it disambiguates. Output format specifics are still absent, but the diagnostic behavior is well disclosed.

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 sentences, front-loaded with the purpose, then the routing trigger, then the disambiguation detail. Tight and every sentence carries information, though the third sentence is somewhat elaborate for the point it makes.

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?

With no output schema, the description should convey what comes back; it does so at the level of outcomes (one of three cases plus a diagnosis of what is wrong). Annotations cover safety and the schema covers both parameters, so the remaining gap — the exact shape of the returned diagnosis — is minor.

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%, including a detailed note that a feed URL is the most useful identifier because the failure is usually that OP3 has never seen the feed. The description reinforces the feed/prefix framing but adds no syntax or format detail beyond the schema, 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?

The description states a specific verb and resource — checking whether OP3 is receiving downloads for a show — and frames the tool as a diagnostic rather than an analytics query, which cleanly separates it from siblings like op3_show_downloads or op3_query_downloads. It even names the failure modes it distinguishes, so an agent knows exactly what question this tool answers.

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?

"Run this first whenever the numbers are zero or a show cannot be found" gives an explicit, actionable trigger condition, plus the implicit converse that it is not the tool to reach for during normal analysis. It does not name alternative sibling tools for adjacent cases (e.g. op3_resolve_show for identifier resolution), so it falls short of a full when/when-not/alternatives statement.

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