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

Annotations already declare readOnlyHint and idempotentHint, and the description adds significant context: it costs nothing, returns problems with line numbers, estimated video length, and credit cost. It also details the checks performed. No contradiction with annotations; adds substantial behavioral disclosure.

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 description is a single paragraph with two sentences. It front-loads the purpose ('Check a guide before saving it') and packs the checks into a list. It's moderately concise but not overly verbose; every clause earns its place. Slightly longer than necessary but well structured.

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?

Given the tool's complexity, the existing output schema (which likely describes the returned problems and estimates), and the read-only annotations, the description covers all essential behavior: checks performed, return types (line numbers, length, cost), and the cost-free nature. 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 description coverage is 100%, so the schema already documents all four parameters. The description adds no parameter-specific meaning beyond what's in the schema; it discusses content checks but doesn't elaborate on how parameters influence behavior. Baseline 3 is appropriate.

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 states a specific verb ('Check') and resource ('a guide'), and enumerates the exact validation checks (unknown DIRECTIVES, undefined VARIABLES, secrets, step executability, missing start, length cap). It clearly distinguishes from siblings like put_guide by positioning itself as a pre-save validation step.

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 phrase 'before saving it' gives a clear temporal context for when to use the tool. It implicitly contrasts with put_guide, but doesn't explicitly name alternatives or state when not to use it. The guidance is clear enough for an agent to infer the intended workflow.

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