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

The description richly discloses behavior beyond the readOnlyHint and openWorldHint annotations: pagination via pagination.cursor, null counts on later pages, absence of publish date, the cost of extra_fetch (1 credit per item), and the per-post authorHandle behavior for collab/tagged posts. It also notes the tool costs 1 credit.

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 front-loaded with purpose and scope, and every sentence adds useful detail about return values, pagination, limitations, and costs. It is somewhat dense and could be structured with bullet points for readability, but it avoids waste.

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?

Given no output schema, the description fully explains what is returned (caption, type, owner), what is missing (publish date, counts on later pages), how to get missing data (extra_fetch or /v1/instagram/post), and the credit cost. An agent has everything needed to call it correctly.

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 80%, so the schema already documents most parameters including extra_fetch's credit cost and cursor usage. The description largely repeats these points and adds no new meaning for count or cache_max_age, though it does explain the pagination flow and extra_fetch outcome slightly beyond the schema.

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 states a specific verb+resource: 'Posts and reels from a profile', and details the return shape ('profile grid, newest first, twelve posts per page, each with its caption, type and owner'). It distinguishes itself from instagram_userReels by including both posts and reels, and routes single-post needs to /v1/instagram/post.

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 gives clear context for using extra_fetch or the /v1/instagram/post endpoint when counts or dates are needed, and implicitly defines its role as the profile grid source. However, it does not explicitly compare to sibling tools like instagram_userReels or instagram_userTaggedPosts or state when not to use this tool.

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