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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds meaningful non-annotation context: a 5-credit cost and the important caveat that very large accounts expose only ~50 recent followers, plus a mitigation. It does not describe rate limits beyond moderation or return 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?

Three tight sentences, front-loaded with purpose and required identifiers, then search/paging mechanics, then the large-account caveat and cost. No filler sentences; every clause carries actionable information.

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 two-required-parameter read tool with no output schema, the description covers purpose, search, paging, cost, and the known data limitation. It never hints at what a page of results contains, but that gap is minor given the simplicity of the operation.

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 coverage is 75%, with query and max_id already documented in the schema. The description adds semantics for the undocumented 'direction' parameter by spelling out 'followers or following', and reinforces that query matches username or name across the whole list, going slightly beyond the bare schema text.

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 opens with a specific verb+resource: 'List or search an Instagram account's followers or following'. It also names the direction enum values and the source of user_id ('from instagramUser'), which distinguishes it from instagramUser/instagramSearch and the parallel tiktokFollowers sibling.

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 states when to use query (to search the whole list, and specifically to find someone in large accounts) and what max_id does (paging). It doesn't explicitly rule out alternatives, but the routing is clear enough for an agent to pick this tool over instagramUser or tiktokFollowers.

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