vk_friends_get_mutual

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

No annotations are provided, so the description must fully disclose behavioral traits. It only states the return type (list of user IDs) but does not mention whether authentication is required, rate limits, what happens with invalid IDs, or behavior when no mutual friends exist. The word 'mutual' implies a read operation, but safety characteristics are not explicitly stated.

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 a single concise sentence that immediately conveys the core functionality. It is front-loaded and contains no extraneous information.

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?

Given 7 parameters, no annotations, and no output schema, the description is insufficient. It does not explain return format details (e.g., pagination via 'count' and 'offset'), default behavior when no parameters are provided (all parameters are optional), or the relationship between 'target_uid' and 'target_uids'. A more complete description would include usage patterns and output structure.

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?

While schema coverage is 100%, the description oversimplifies by stating 'two users', but the schema supports multiple target_uids via the 'target_uids' array parameter. This discrepancy could mislead the agent about parameter combinations. The description adds no explanatory value beyond the schema's own parameter descriptions.

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 clearly states it returns a list of user IDs of mutual friends of two users. It identifies the specific resource (mutual friends) and action (get list). This distinguishes it from siblings like vk_friends_get which returns a user's own friends, and vk_friends_are_friends which checks friendship status.

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 description provides no guidance on when to use this tool versus alternatives. It does not mention scenarios (e.g., finding common connections), conditions (e.g., users must exist), or exclusions. No reference to other tools or context for selection.

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