MCP Scrcpy Vision

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

With no annotations provided, the description carries full burden. It discloses the tool's read-only nature (finds/returns) and output format (center coordinates), but lacks critical behavioral details: whether it returns multiple matches, timeout behavior, screen state requirements (e.g., requires screen to be on), or error handling. For a tool with 5 parameters and no annotation coverage, this is a significant gap.

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, well-structured sentence that front-loads the core action (finds UI elements), specifies filters, and states the return value. Every word earns its place with no redundancy or fluff.

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 5 parameters, 0% schema coverage, no annotations, and no output schema, the description is moderately complete. It covers the purpose, filters, and return format adequately, but lacks details on behavioral traits (e.g., match limits, errors), parameter semantics beyond listing, and does not fully compensate for the missing structured data.

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 0%, so the description must compensate. It lists the four filter parameters (text, resource-id, class, content-desc) and implies the 'serial' parameter identifies the device, adding meaningful context beyond the bare schema. However, it does not explain parameter interactions (e.g., whether filters are AND/OR), format expectations, or the 'serial' parameter's purpose in detail.

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 verb 'finds' and resource 'UI elements in the current screen', specifying the filtering criteria (text, resource-id, class, content-desc) and the return value (matching elements with center coordinates). It distinguishes itself from sibling tools like android.ui.dump (which likely provides raw UI hierarchy) by focusing on filtered element discovery with actionable coordinates.

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 implies usage when needing to locate UI elements for interaction (e.g., tapping), but does not explicitly state when to use this tool versus alternatives like android.ui.dump or direct input tools. It provides context about the current screen scope but lacks explicit guidance on prerequisites or exclusions.

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