instagram_upload_reel

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

The description adds meaningful behavioral context beyond the annotations: it specifies the video format (vertical 9:16), the prerequisite environment variable, and the fact that thumbnail is optional. This complements readOnlyHint=false and openWorldHint=true without contradicting them. It does not mention failure behavior or side effects, but annotations cover the basic write nature.

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?

The description is extremely concise and well-organized: it leads with the purpose, then lists requirements, parameters, and return values. Every sentence is informative and there is no fluff. It is appropriately front-loaded and easy to scan.

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?

The description covers the core aspects needed to call the tool: purpose, input format, environment variable, parameters, and return structure. Given that an output schema exists and annotations are present, this is adequately complete. It does not mention rate limits or error handling, but for a publish action with clear inputs and outputs, this is sufficient.

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 all parameters are already well-documented. The description's parameter list is a concise summary but adds no new information beyond the schema. The schema provides more detail (absolute path, max length for caption, behavior when thumbnail omitted), so the description meets the baseline but does not exceed it.

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 verb 'publish' and the resource 'reel', and explicitly mentions the vertical 9:16 format requirement, which distinguishes it from other upload tools. This is specific and understandable in isolation.

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?

It provides clear context for when to use this tool (publishing a reel, expects vertical video) and even mentions the required environment variable INSTAGRAM_ALLOW_WRITES=true. However, it does not explicitly contrast with sibling upload tools (upload_photo, upload_video, etc.), so the guidance is clear but not fully exclusionary.

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