fx_snapshot

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

No annotations are provided, so the description must disclose behavioral traits. It only mentions the output (map with refs) but not any side effects, performance implications, or requirements (e.g., does it require a loaded page?). It doesn't describe the return format or whether it makes a network request. This is insufficient for a tool with zero annotation support.

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 short fragment, which is concise and front-loaded with the core purpose. It's not bloated, but it omits some useful context (like what the map contains). Still, for zero-param tools, this level of brevity is acceptable.

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 zero parameters and no output schema, the description should explain what the tool returns and how to use it. It covers the 'use refs' part, but doesn't describe the structure of the map (e.g., what elements are included, how refs are formatted). For a simple snapshot tool, this might be sufficient, but there's room for more detail on expected return behavior.

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?

The tool has zero parameters, so the schema already covers everything (100% coverage). The description doesn't need to explain parameter semantics. The baseline for zero-param tools is 4, and there's no missing information to penalize.

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 states the resource (interactive-element map) and its output (refs), but lacks an explicit verb like 'get' or 'snapshot'. It's a noun phrase that implies retrieval, which is understandable in context but not fully specific. It does distinguish from siblings by mentioning refs for interaction tools, which is useful.

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 indirectly tells the agent that refs from this tool are used in fx_click/fx_type/..., implying this should be called before those interactions. However, it doesn't explicitly say when to use this tool vs. alternatives, nor does it mention conditions like 'call after navigation' or 'when you need element references'. The guidance is implied rather than explicit.

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