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

Annotations mark it non-read-only and non-destructive; the description adds real behavioral context beyond that — nothing is published, nobody is notified, so it runs unprompted, the filename must be unique per show, accepted formats are enumerated, and it requires a Cotlet API key with app access. These are exactly the facts an agent needs before invoking a write tool.

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?

Front-loaded with the core action and efficiently packs formats, uniqueness, non-publication, return value and auth into a few sentences. It loses a point for stating 'Nothing is published' twice, which is a genuine redundancy rather than emphasis.

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?

No output schema exists, yet the description names the returned media_file_id and its downstream use. Combined with the non-publication guarantee, format constraints and auth requirement, an agent has everything needed to call this correctly and chain it into create_episode.

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 schema already documents show_id, file_url and file_name including defaults. Description reinforces the format list and uniqueness constraint but adds little beyond what the schema's own parameter descriptions state, so 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 ('Add an audio, video or PDF file to your media library from a URL') and scopes it ('one show'), which cleanly separates it from libsyn_upload_transcript (transcripts) and libsyn_create_episode (drafts). An agent can pick this over its siblings without opening the schema.

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?

Gives clear context: it fetches from a URL, nothing is published, and the returned media_file_id should be attached to a draft with create_episode. That routing to the next tool is explicit. It stops short of stating a when-not-to-use case or prerequisite ordering, so it is strong but not complete.

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