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

Beyond readOnlyHint=true, the description discloses what the tool actually does (compiles against the real type definitions for that version), what it returns (diagnostics with line, column, TS error code and message, plus the module versions it compiled against), and which failure class it catches. No contradiction with 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?

Three sentences, each earning its place: what it does, what it returns, and when to use it. The highest-value distinguishing fact (real TypeScript compiler against actual type definitions) is front-loaded, with zero filler.

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?

For a tool with no output schema, the description compensates well by naming the diagnostics fields (line, column, TS error code, message) and the module-versions report. Parameters are fully documented in the schema. It falls short of a 5 only because the response envelope isn't specified and there's no mention of compile cost/time traits.

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 baseline is 3 per the rubric. The description adds a modest bit of cross-parameter meaning by tying version to 'the actual type definitions for that version' and referencing module versions, but the schema already documents code, channel fallback, and version constraints thoroughly.

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 specific verb (compiles), resource (behavior pack script against the actual @minecraft/server type definitions), and mechanism (real TypeScript compiler). The 'Catch non-existent APIs and calls removed in later versions' clause clearly distinguishes this from sibling validation tools like validate_json, validate_python, and validate_command, which check syntax rather than type-check script against versioned API definitions.

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?

'Catch non-existent APIs and calls removed in later versions here' gives an explicit trigger condition, and the note that Bedrock scripting APIs written from memory are the most common source of silent failures provides a concrete when-to-use scenario. It stops short of a 5 because it doesn't name alternatives or give when-not-to-use exclusions.

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