Screen MCP

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

No annotations are provided, so the description carries the full burden. It discloses that the tool returns metadata (not full payload) and is used for discovery and validation, which adds useful context. However, it lacks details on behavioral traits such as error handling, performance, or side effects, leaving gaps for a tool with no annotation coverage.

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 front-loaded with the core purpose in the first sentence, followed by usage guidelines in the second. Both sentences earn their place by adding value beyond structured fields, with zero wasted words, making it highly efficient and well-structured.

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 the tool's moderate complexity (1 parameter, no annotations, but with an output schema), the description is mostly complete. It explains the purpose, usage, and workflow role adequately. However, it could improve by addressing potential errors or the format of returned metadata, though the output schema mitigates some of this need.

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 input schema has 1 parameter with 0% description coverage, so the description must compensate. It implies the parameter 'timeline_id' is required (as per the schema) by referencing it in the workflow context ('after `start_timeline_capture`'), but does not explicitly explain its semantics or format. Since there is only 1 parameter, the baseline is 4, but it could be higher with more 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 specific action ('Return timeline session metadata') and resource ('timeline session'), distinguishing it from siblings like 'get_timeline_chunk' (which retrieves payload data) and 'get_screenshot_manifest' (which handles screenshots). It explicitly mentions what it does not return ('without the full payload'), enhancing differentiation.

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 explicit guidance on when to use this tool: 'Use this as step 2 after `start_timeline_capture`'. It also specifies the purpose ('to discover `total_chunks` and validate integrity metadata'), clearly indicating its role in a workflow and distinguishing it from alternatives like 'capture_timeline' or 'list_monitors'.

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