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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely new context beyond them: that it returns public data, changes nothing, and costs 1 credit per result with a 1-credit minimum per request. It does not discuss rate limits or behavior for private/protected accounts, which keeps it below a 5.

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?

Two tight sentences: the first defines the operation and its output fields, the second covers paging, read-only semantics and billing. Nothing is wasted and the core purpose is front-loaded.

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?

With no output schema, the description usefully enumerates returned fields and covers pagination and credit cost for a 3-parameter read tool. It leaves gaps around behavior for private accounts and error/empty results, but nothing essential to invoking it correctly is missing.

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 three parameters (username, count, cursor) are already documented with format examples and ranges. The description's cursor mention duplicates rather than extends the schema, 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 ('List the accounts an Instagram user follows') and enumerates the returned fields (username, full name, profile picture, private/verified flags). The phrasing 'follows' naturally distinguishes it from the sibling instagram_followers, so an agent can route correctly 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 paging guidance ('Page through the list with `cursor`') but no explicit when-to-use versus alternatives such as instagram_followers or instagram_user. Usage is implied by the resource description rather than stated as a selection rule.

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