Validate an authored diagram

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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuine value by disclosing the return shapes: "OK with node and edge counts" versus "INVALID with one line per problem (block:line:column, and a suggestion when one exists)." It stops short of saying whether any files or state are touched on disk, but the "locally, without pushing it" phrasing covers the main concern.

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 sentences, front-loaded with the core action and the non-pushing constraint, followed by a short next-step instruction. No filler or redundancy.

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 carries the burden of explaining results and does so precisely (OK counts vs. INVALID per-error lines with location and suggestion). For a single-parameter, read-only validation tool, nothing an agent needs to call it correctly 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?

There is only one parameter and the schema already documents it at 100% coverage, including the ```arcsync fence and Mermaid/@{} metadata syntax. The description restates the same fence concept without adding format or size guidance, so the baseline 3 applies.

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 names a concrete verb ("Check") and resource ("ArcSync diagram source (```arcsync blocks)") and immediately scopes it as local validation "without pushing it," which cleanly separates it from push_diagram and the parse/delta siblings.

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?

It gives an explicit workflow: run validate_diagram, fix every error, then call push_diagram. The alternative (pushing) is named along with the condition that selects validation first, so no inference is required.

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