ui_detect_dev_serverDetects running local dev servers by checking the UI_LOOP_URL env, Next.js lock files, and common ports like 3000-3005 or 5173. Returns candidate base URLs for connecting UI tools.
Find running local dev servers (UI_LOOP_URL env, Next.js .next/dev/lock, common ports 3000–3005/5173/4200/8080). Returns candidate base URLs.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond those flags: the concrete detection heuristics and the fact that results are unverified 'candidate' URLs rather than confirmed servers.
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?
Two tight sentences with no filler: the first gives the action plus detection sources, the second gives the return shape. Front-loaded and appropriately sized for a zero-parameter tool.
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?
With no output schema, the description correctly supplies the return contract ('candidate base URLs') and the detection sources. It stops short of saying what an empty result means or whether multiple candidates are ranked, but nothing essential for correct invocation is missing.
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 takes zero parameters, so the baseline is 4 — there is nothing for the description to clarify and no ambiguity an agent could stumble into when invoking it.
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 ('Find running local dev servers') and enumerates exactly how detection is performed (UI_LOOP_URL env, Next.js .next/dev/lock, specific ports). It also states the return type. No sibling (ui_capture, ui_diff, ui_list, etc.) overlaps this discovery function, so an agent can select it unambiguously.
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?
Usage is implied — an agent would call this to discover a base URL before capture/assert operations — but the description never states when to use it or what to do if detection fails. There is no explicit alternative to route against, so the gap is moderate rather than severe.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.