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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered and the bar is lower. The description adds genuinely new behaviour: the return payload is in source coordinates and times, and the empty-result case should trigger a request to the user. It does not mention permissions or failure modes beyond the empty case.

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 short sentences, front-loaded with the purpose and followed by the actionable edge case. No filler, no restatement 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?

For a read-only tool with no output schema and only two parameters, the description gives an adequate sense of the return shape and the empty case. It is incomplete on the undocumented assetId and on sibling differentiation, and it omits any mention that assetId must reference a specific asset in the open project.

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 only 50%: projectId is well documented in the schema, but assetId carries no description anywhere. The description says nothing about either parameter, so it fails to compensate for the undocumented assetId (the tool's only asset-scoping input).

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 ('Read the user's preview pen points') plus the scope of what comes back (source coordinates and times), so the agent knows exactly what is returned. It does not distinguish this from near-neighbours such as track_points or preview_frame, which is the main clarity gap.

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 only conditional guidance is about the empty state ('When no points exist, ask the user to place one'), which is a behaviour rule rather than when-to-use guidance. Nothing tells the agent when to prefer this over track_points, preview_range, or preview_timeline, or what prerequisites (e.g. an open project) apply.

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