SVG Editor MCP demonstrates solid tool design with clear naming (verb_noun pattern), comprehensive descriptions (avg 180 chars), and well-structured schemas using Zod validation. All 8 tools have input/output schemas and descriptions. Tool annotations (readOnlyHint, destructiveHint, idempotentHint) are properly applied. Key strengths: surgical edit operations with detailed selector documentation, clear error handling via fail() wrapper, and resource linking. Weaknesses: some parameter descriptions lack format constraints (e.g., svg content max 1000000 bytes stated in description but not enforced in schema); operations array in svg_apply uses oneOf with implicit discriminator rather than explicit tagged union; svg_commit visibility restricted to 'app' only, limiting discoverability.

• Add explicit discriminator to svg_apply operations schema: use 'op' as the discriminator field and provide a discriminator mapping. This enables LLMs to construct valid operations without trial-and-error.
• Restore svg_commit to model visibility (uiMeta(['model', 'app'])) so the LLM can plan the svg_apply → svg_commit workflow. Document that svg_commit is app-initiated but model-callable.
• Enforce max-length constraints in Zod schemas using .max() for strings and .refine() for byte counts. Move constraint validation from description text to machine-readable schema.
• Enhance error handling: categorize errors (e.g., 'Invalid selector: #nonexistent, try svg_inspect() to list available IDs') and provide recovery hints. Use error.code or error.type to signal retryable vs. fatal.
• Clarify svg/content parameter precedence: document 'svg takes precedence if both provided' or make them mutually exclusive via oneOf in the schema.

Inferred effective spec: 2025-06-18+.

• Current-spec patterns present: structured tool output, tool annotations