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

No annotations are supplied, so the description carries the full burden. It does add genuinely useful behavioral facts: results are limited to public Reels, each request costs 1 credit, and a Bearer API key is required. It says nothing about pagination behavior despite a cursor parameter, nor about rate limits or result shape.

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 purpose in the first clause, followed by short operational facts. There is minor waste in the boilerplate fragment 'Platform=instagram resource=audio' and a doubled period, but no sentence is redundant at length.

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 two-parameter, non-destructive list endpoint with a complete schema, the description covers purpose, cost, auth, and public-only scope. It omits pagination expectations and any hint about what a returned Reel record contains, leaving gaps that a fully self-sufficient definition would close.

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 both parameters are already documented in the schema (audio_id as 'Instagram audio / track id', cursor as the pagination cursor). The description only restates the audio-id scoping already implied by the schema, adding no format or syntax detail. 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: 'List public Reels that use an Instagram audio track (by audio id)'. An agent can immediately tell what data this returns and that it is scoped to a single audio id. It does not explicitly contrast with siblings such as instagram_search or instagram_media/info, which keeps it from a 5.

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?

Use is implied by the resource wording – call this once you have an audio id and want the Reels that use it – but there is no explicit when-to-use/when-not-to-use guidance and no named alternative. Nothing tells the agent whether instagram_search could also surface this content.

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