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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds the useful fact that the call is free and enumerates what comes back, but it says nothing about rate limits, failure modes for bad feeds, or pagination behavior tied to the limit parameter. That is adequate but not rich context beyond the annotations.

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?

It is a single sentence with no filler, and the return fields are front-loaded after the purpose. However, the raw route string 'GET /x402/podcast-lookup?feed=' is low-value implementation detail for an agent, and 'FREE' at the start is redundantly echoed by '— free' at the end.

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 three-parameter tool with no output schema, the description does the important extra work of listing the response fields, which is exactly what the missing output schema would otherwise leave unclear. Remaining gaps are minor: no guidance on how limit affects the episode list and no pointer to the transcript sibling.

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 feed, limit and payment are each documented in the schema, including the x402 challenge-then-retry flow. The description only restates the feed input ('RSS feed URL or Apple Podcasts id') and adds nothing about limit or payment 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: discovery of show metadata and an episode list from an RSS feed URL or Apple Podcasts id, with enumerated return fields (titles, dates, durations, audio urls, hasTranscript). The hasTranscript flag implicitly points at sibling get_podcast_transcript, but the split between lookup and transcript retrieval is never stated outright, so sibling differentiation is only partial.

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?

There is no explicit when-to-use guidance. The word 'discovery' plus the hasTranscript flag hint that this is the first step before pulling a transcript via get_podcast_transcript, but the agent must infer that. Nothing says when not to use it or what the tradeoff is versus the transcript sibling.

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