Read the value at a Luau path/expression (precise slot read)

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), yet the description adds substantial behavioral detail beyond them: evaluation as `return <expression>` under pcall, clean { error } on a bad path, the exact result shape (type/value/isTable, length, keys capped at 50, keysTruncated), pcall-guarded key reads, and the loadstring/load and active-client requirements.

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 core purpose and a dense, useful body. It is long and the trailing boilerplate ('Phase: observe; cost=medium... On failure: inspect tool-schema...') partly restates annotations and metadata, but the bulk of the text carries real informational weight.

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 fully specifies the return contract ({ type, value, isTable, length?, keys?, keysTruncated? } or { error }), the failure mode, and runtime prerequisites. Nothing an agent needs to invoke or interpret this tool 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%, so both parameters (expression, threadContext) are already documented in the schema with examples. The description reinforces rather than extends them — it clarifies the `return <expression>` evaluation form but adds little syntax or constraint meaning beyond the schema, matching the baseline for full coverage.

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+resource ('Evaluate a single Luau expression and report exactly what lives at that slot') and explicitly positions itself against a sibling ('the counterpart to write-path-value'). An agent can distinguish it from eval-expression, run-luau, and write-path-value from the description alone.

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?

Gives concrete usage context: read a precise location after a heap scan points you at it, or spot-check any value/global/field during analysis, and names its mutation counterpart write-path-value. It stops short of explicit when-not or naming read-style alternatives like eval-expression, so it is clear context without full routing rules.

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