Preview a symbol

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

Annotations already establish readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds substantial behavioral value beyond that: the output format (markers per record kind, per-kind count line, legend) and the coordinate semantics ('10 units = 1 grid'). This tells an agent exactly what the rendered result will contain without contradicting the annotations.

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 core purpose is front-loaded in the first clause, followed by the output contents and a necessary coordinate-system note. Every element earns its place — the record-kind list, though long, tells the agent what output to expect. It is dense rather than padded, though the single-sentence structure with a long enumeration makes it slightly harder to parse than it could be with clearer segmentation.

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 present, the description carries the burden of explaining return values, and it does so well: output format, included record kinds, count line, legend, and coordinate units are all covered. All parameters are documented in the schema and the safety profile is in annotations. What's missing is minor — error behavior for invalid component names or missing files — but nothing an agent needs to invoke the tool correctly is absent.

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 100%, so the schema already fully documents all 6 parameters, setting the baseline at 3. The description does add marginal value by explaining the coordinate system ('Coordinates are in schematic units (10 units = 1 grid)'), which reinforces the meaning of scale, and clarifies that pins render 'with designators.' But it doesn't substantially extend what the schema already says.

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 opens with a specific verb+resource+format: 'Render an ASCII art visualisation of a schematic symbol from a SchLib file.' The precision of 'schematic symbol' cleanly separates it from the sibling render_footprint (PCB footprints), and the visualization framing distinguishes it from read_schlib (raw data access). The exhaustive enumeration of record kinds further pins down 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?

The usage context is strongly implied: an agent can infer this tool is for visually previewing a SchLib symbol, versus render_footprint for footprints or read_schlib for structured data. However, the description never explicitly states when to use this tool over those alternatives, and there are no exclusions or when-not-to-use conditions.

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