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

Annotations already provide readOnly, idempotent, and non-destructive hints. The description adds tier-dependent output behavior (stitched-with-ad vs bare audio), which is valuable and not derivable from annotations or schema. This exceeds the baseline expectation.

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?

Two sentences, both informative and free of redundancy. The main action is front-loaded, and the second sentence adds a meaningful nuance about tiers. No wasted words.

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 simple one-parameter resolver with robust annotations, the description covers the core purpose, the input implied by 'article', and the output type (URL). No output schema exists, so the return description suffices. Edge cases are not necessary at this complexity level.

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 has only 'slug' with no description, and schema coverage is 0%. The description clarifies that the slug refers to an article, but does not explain the slug format or how to obtain it. It offers partial compensation for a simple parameter but not complete semantics.

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 states the tool's function with a specific verb 'Resolve' and a specific resource 'playable audio URL for an article'. It distinguishes itself from siblings like get_article by focusing on audio URL resolution. The tier-dependent return detail further anchors its purpose.

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?

The description implies when to use it: 'for an article' indicates it pairs with an article identifier (slug). It doesn't explicitly name alternatives or exclusion criteria, but the context is clear. Lacks explicit 'use this instead of...' guidance, so not a 5.

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