Capture chart image

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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds the isolated headless browser context and the ephemeral viewer lifecycle ('browser and ephemeral viewer close afterward unless keepRuntimeOpen is true'), which is valuable beyond the annotations.

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 tight sentences; the first immediately states the action and output, the second adds the lifecycle caveat. No redundant wording.

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 simple, read-only snapshot with optional parameters, the description covers the core behavior, output type, and runtime side effect. It does not detail PNG encoding or compare with tradingview_snapshot, but that is a minor gap given the tool's simplicity and strong annotations.

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?

With 0% schema description coverage, the description only explains keepRuntimeOpen's side effect; width and height are left to their names and schema constraints. This is partial compensation, not full semantic coverage.

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 uses a specific verb ('render') and resource ('the local chart viewer'), states the output ('return a PNG for visual analysis'), and the qualifier 'local chart viewer' distinguishes it from tradingview-based siblings like tradingview_snapshot.

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 phrase 'for visual analysis' hints at a use case, but there is no explicit when-to-use guidance, no exclusions, and no mention of alternatives such as chart_analyze or tradingview_snapshot.

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