Write a SchLib

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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description is consistent while adding substantial context beyond those flags: the replace-by-default behavior, the coordinate-unit trap ('10 units = 1 grid square, not mm'), the pin body-attach vs tip convention, the response echo of computed body_end and tip, and the hard '|' separator restriction. This is exactly the kind of failure-mode disclosure agents need.

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 dense paragraph that front-loads purpose and the append decision before diving into details. Every sentence carries substantive guidance, though the enumeration of ~15 primitive kinds partially duplicates structure already visible in the schema array definitions.

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?

For a tool of this complexity — a huge nested symbol schema and no output schema — the description covers the operational essentials an agent cannot safely infer: append/replace, units, pin geometry, multi-part tagging, the '|' constraint, and the response echo. The read-modify-write/raw_params round-trip behavior is left to the schema, which documents it exhaustively on every record type, so nothing critical 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?

Schema coverage is 100% and the schema's own pin descriptions are already unusually rich. The description still adds meaning beyond it: the append-vs-replace decision, the 'not mm' unit warning, the multi-part convention (part_count + owner_part_id), and the '|' validation constraint. That meaningful supplement pushes it above the baseline 3 for fully-covered schemas.

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+resource: 'Write schematic symbols to an Altium .SchLib file'. The SchLib resource paired with the write verb clearly distinguishes it from siblings like read_schlib, write_pcblib, and write_libpkg. The symbol-composition list (pins, rectangles, parameters, footprints, ...) reinforces exactly what the tool produces.

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?

Provides clear context: the tool creates or modifies schematic symbol libraries, and the key operational decision is spelled out — 'set append: true to add to an existing library instead of replacing it'. However, it never names an alternative tool or states an explicit when-not-to-use condition, so it stops short of a 5.

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