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

Beyond the readOnly/idempotent/non-destructive annotations, the description discloses the verdict vocabulary ('inside', 'intrudes', 'unknown'), the meaning of 'unknown' for TikTok, that a reason is returned instead of a guess, and which inputs produce errors. This is rich behavioral context that annotations alone would not supply.

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 tight sentences with no waste: purpose first, then the sibling alternative, then return/error behavior. Every clause earns its place and the most decision-relevant information is front-loaded.

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 an output schema present, the description need not explain return values, yet it still names the verdicts and the 'unknown' case. It also covers the error paths and the sibling relationship, leaving nothing important for an agent to guess.

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 100%, so the per-parameter meanings are already documented as left/top edges and width/height in px. The description adds the global framing ('in px on the placement's own frame, origin top-left'), but that is largely a restatement of the schema's coordinate descriptions, so the baseline 3 is appropriate.

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 ('Check whether a rectangle ... stays inside the placement's safe area') plus the exact coordinate frame and origin. It is clearly distinguishable from the sibling get_social_media_placement, which is named as returning raw insets instead of a verdict.

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?

Explicitly says 'Use this to validate a layout before export' and routes the agent to get_social_media_placement when raw insets are wanted. The when-to-use and the alternative are both stated, so no inference is needed.

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