sch_place_junction

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

With no annotations, the description carries the full burden and does well: it discloses visual behavior (dark red with lock marker), the redundant-on-T consequence ('just sits on top of the blue one'), and that the tool operates on the 'active schematic'. It stops short of stating prerequisites such as what happens when no schematic document is active or whether the placement is undoable.

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?

Front-loaded with the core action, then the exclusion rule, then the inclusion rule — a logical order. The middle paragraph is slightly long (color and lock-marker detail could be trimmed) and the all-caps 'A T NEEDS NONE' is emphatic rather than efficient, but every sentence carries real differentiation.

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 the brief 'Returns' line is a bonus rather than a necessity, and both parameters are covered with units. What is missing for a no-annotation mutation tool is failure/precondition behavior (no active document, off-grid coordinates). Otherwise an agent has everything needed to call it correctly.

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% — x and y have only integer titles — but the description compensates by supplying the unit ('X coordinate in mils', 'Y coordinate in mils'), which is the critical missing semantic. It does not clarify absolute-vs-relative placement or grid snapping, so it falls short of a 5.

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 first sentence states a specific verb and resource — 'Place a MANUAL junction at coordinates on the active schematic' — and the emphasis on MANUAL immediately separates it from the automatic junctions Altium creates. The agent can distinguish this tool from sibling schematic placement tools (sch_place_wires, sch_place_bus_entry) without opening the schema.

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?

Explicit when-not guidance: 'A T NEEDS NONE' followed by an explanation that Altium auto-draws junctions on T's, including for wires this server places. Then explicit when: 'Use it only where two wires CROSS and must connect.' Both the positive and negative conditions are stated with the reason behind them.

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