Capture an Android device screenshot and save it to a specified file path, returning status, path, and byte size without embedding the image inline.
Capture a screenshot and save it to save_path, returning {status, path, bytes}
(no inline image — use when you only need the file).
| Name | Required | Description | Default |
|---|---|---|---|
| serial | No | ||
| save_path | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose the return shape ({status, path, bytes}) and confirms no inline image is returned. However it says nothing about whether an existing file at save_path is overwritten, whether parent directories are created, or what happens if the capture fails.
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?
A single tight sentence plus a short parenthetical discriminator; the output artifact and the routing hint are front-loaded with zero wasted prose.
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?
An output schema exists so return details are covered, and the description adds the key behavioral fact (file-only, no inline image) plus the destination parameter. The only real gap is the undocumented `serial` parameter and file-overwrite 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?
Schema description coverage is 0%, so the description must compensate. It adequately explains save_path (the destination of the capture) but says nothing about `serial`, leaving the device-selection/default behavior undocumented in both schema and description.
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 ('capture a screenshot and save it to save_path') and names the produced artifact. It also implicitly separates itself from the inline-image siblings by saying 'no inline image', though it never names capture_screen or capture_screen_base64 directly.
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?
'use when you only need the file' gives an explicit selection condition that routes the agent away from the inline-image variants. No exclusions or sibling names are given, but the criterion is concrete enough to choose correctly.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.