Slim one MCP tool definition

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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered; the description adds genuinely new behavior by defining what the 'slim form' actually keeps (name, type, required marker) and that char/token deltas are computed against the input. It stops short of describing edge-case handling or failure modes.

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 verb and resource, and every clause carries information. The single long sentence is dense but not padded, and no filler precedes the point.

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 return contract need not be spelled out, yet the description helpfully flags that the delta metrics come back with the slim definition. For a single-parameter transformer with full schema coverage and rich annotations, nothing an agent needs to invoke 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?

Schema coverage is 100% and its description already specifies that the input is a serialised JSON object requiring a non-empty 'name', with bare strings rejected. The description adds nothing beyond that, so 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?

States a specific verb (rewrites/slims) plus the exact resource (a single MCP tool definition, name/description/inputSchema) and the form produced. An agent can tell this apart from siblings like demo_compare_formats or demo_encode_toon without opening any 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?

Usage is implied by the transformation described, but the description never says when to reach for this tool versus the sibling format/diff tools (demo_compare_formats, demo_encode_toon, demo_build_tool_manifest). No prerequisites or exclusions are stated.

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