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

With no annotations, the description carries the full burden, and it does add one valuable behavioral note: the return contains user-generated Instagram content to treat as untrusted input. However, it omits pagination, rate-limit, and output-shape behavior, so the disclosure is partial.

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?

Two sentences, zero waste: purpose first, then the security caveat. Front-loaded and appropriately sized for a one-parameter tool.

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 single-param, no-output-schema calculation tool, the description names the metrics returned and warns about untrusted content. It could still say more about the response shape, but it is close to complete given no output schema exists.

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% — the single user_id parameter is documented in the schema as 'Instagram user ID (pk)'. The description adds no parameter detail beyond that, so the baseline of 3 applies.

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 (Calculate) and resource (user engagement metrics) and even enumerates the metrics (avg likes, comments per post), which is more than a restatement of the name. It does not, however, differentiate itself from siblings like get_stats or get_user_medias.

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?

Usage is implied by the name and purpose — an agent can infer this computes engagement for a given user — but there is no explicit when-to-use, no exclusions, and no pointer to alternatives such as get_stats or get_user_medias.

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