browser_snapshot_frame

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It discloses the nested frame syntax with an example, which is useful behavior not obvious from the schema. However, it doesn't mention what the snapshot output is (e.g., image path, base64), what happens if the selector is invalid, or explicitly confirm that it's a read-only operation. The nested-frame guidance adds some value but leaves significant gaps.

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 two sentences long and immediately states the core purpose. The example is concisely embedded and adds real value without fluff. Every word earns its place.

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?

This is a simple tool with one parameter and no output schema or annotations. The description explains the selector mechanics well, but it doesn't state what the snapshot returns (e.g., a screenshot image) or how it relates to browser_snapshot. For an agent to fully understand the tool's effect and output, more information is needed, though the simplicity keeps it adequate.

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% since the only parameter, frameSelector, is described in the schema. The description adds value by providing a concrete example ('iframe#pplayer_iframe >> iframe#modulePlayerIframe') that clarifies the chaining format beyond the schema's generic description. This extra guidance helps the agent construct valid selectors.

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 the tool's purpose: 'Snapshot a single iframe by selector.' It specifies the action (snapshot), the resource (iframe), and the method (by selector). This distinguishes it from sibling tools like browser_snapshot which captures the full page, and browser_frame_probe which likely inspects frames.

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 clear context that this tool is for snapshotting a single iframe, and gives a specific example of using ' >> ' for nested frames. While it doesn't explicitly state when not to use it or name alternatives, the purpose is distinct enough that an agent can infer when to select this tool over siblings.

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