instagram_highlights

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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description still adds non-obvious traits: the exact returned fields and the 3-credit cost, which is decision-relevant for an agent budgeting calls.

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 short sentences, front-loaded with what the tool returns, then the routing hint, then the cost. No filler or repetition of the title.

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 correctly compensates by naming the returned fields, and it covers cost and the follow-up call. It is close to complete; the only gap is not stating whether user_id or username is required for a successful call.

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% and both parameters already document the user_id-or-username alternative, so the baseline is 3. The description adds meaning by tying an 'id' to the highlight-items flow, clarifying an identifier concept the schema does not surface.

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 ('Get Instagram story highlights') and describes the payload fields returned (title, cover image, item count). It is distinguishable from the near-named sibling instagram_highlight, which it explicitly routes to for item-level data.

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 tells the agent the follow-up path ('Pass an id to /v1/highlight for its items'), which is genuine routing guidance to a sibling. It does not, however, say when to prefer this over instagram_stories or whether a user_id/username is mandatory, so the when-to-use context is clear but incomplete.

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