Look up an Instagram account by handle

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

Annotations already mark it read-only, non-destructive, and open-world, and the description reinforces this with concrete details: read-only, 0 credits, no new permission, no reconnect. It goes beyond annotations by disclosing the ambiguous error behavior across personal/private/age-gated/nonexistent accounts, and that data comes straight from Meta rather than a scraper — behavior an agent cannot know from schemas.

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?

The description is lengthy but every section earns its place: primary function, cross-tool warning, and error semantics. It front-loads the essential purpose and uses bold for critical constraints. Slightly verbose in the error explanation, but the density of critical usage information justifies the length.

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 tool with no output schema, the description covers all necessary context: accepted input formats, required authentication context (professional account), the relationship to manage_meta_partnership_creator, and the error-to-caller guidance. An agent has everything it needs to invoke this tool correctly and interpret results without additional lookups.

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% with both parameters already described. The description adds value by enumerating accepted handle formats (bare, @, full link) and the normalization step, plus the condition for omitting pageId. This exceeds the baseline of 3 that schema coverage warrants, though it doesn't elaborate on every edge case for pageId.

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 states a precise action — converting an Instagram @handle into a numeric ID plus profile data — and names the two distinct jobs (ID lookup and brand sizing). It distinguishes itself from the sibling manage_meta_partnership_creator by spelling out that it supplies the numeric IDs that tool requires, making its unique role unmistakable.

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 explicitly directs when to call this tool ('CALL IT BEFORE manage_meta_partnership_creator'), explains why (that tool rejects non-Meta IDs with an ambiguous error), and hard-scopes usage to professional accounts. It also warns about the four failure cases returning the same refusal, giving the agent clear guardrails on what not to infer.

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