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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-network behavior are covered structurally. The description adds one genuinely useful behavioral fact — the 5-credit cost — but says nothing about pagination behavior, rate limits, or whether private accounts fail.

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?

One dense, front-loaded sentence organized by mode, followed by a cost note. Every clause maps to a mode or parameter, so little is wasted, though the mode list is packed tightly enough to require a second read.

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 an 8-mode, 11-parameter tool with no output schema, the description covers mode selection well but omits pagination mechanics (end_cursor, pagination_token) and the count cap, which an agent needs to page through results 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 only 18%, so the description must compensate, and it does partially by binding modes to user_id, shortcode/url, comment_id, and username. However, several of the 11 parameters — count, end_cursor, pagination_token, media_id, code_or_id_or_url — get no explanation anywhere, leaving the pagination and count semantics undocumented.

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?

Names a specific resource (Instagram content) and enumerates the exact modes it serves — posts, reels, tagged posts, single media, comments, comment replies, stories — each tied to its identifying parameter. An agent can distinguish it from instagramUser, instagramSearch, and instagramFollowers 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?

The mode-to-parameter mapping (user_id for account feeds, shortcode/url for a single post, comment_id for replies, username for stories) effectively tells the agent which mode to pick and what it requires. It stops short of naming alternatives or when-not-to-use conditions versus instagramSearch/instagramUser.

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