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

Annotations declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds the pagination contract, the 422 private_account error, and a credit cost. That is useful behavior beyond the annotations, though it doesn't cover rate limits or partial-failure behavior.

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?

Four short sentences, front-loaded with the purpose, then pagination, then failure mode, then cost. Every sentence carries distinct information and nothing repeats the schema.

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 still describes the return shape (a page of accounts plus total follower count, next_cursor for continuation) and the one error path, so an agent has everything needed to call and iterate 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 coverage is 100%, so the baseline is 3, and the description raises it by explaining the cursor round-trip ('Pass next_cursor back as cursor') and confirming the public-account constraint that governs the user_id/username pair.

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+resource: retrieving one page of the accounts that follow a public account, plus the total follower count. An agent can distinguish it from instagram_following by the 'follow' direction, though no sibling is named explicitly.

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?

Explains pagination mechanics ('Pass next_cursor back as cursor... null means no more pages') and the private-account failure mode, which is genuine usage guidance. It never states when to choose this over instagram_following, instagram_likers, or other account-listing siblings.

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