cache.invalidate — drop an instance from the executor's instance cache

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

Goes well beyond the annotations by disclosing the loadstring-based target resolution, the type-guarded cache-library requirement, the pcall wrapping, and the { ok } / { error } return shape on failure. It also restates the mutating/live-state nature in prose, consistent with destructiveHint=true and readOnlyHint=false.

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 core purpose is front-loaded and the technique/rationale is genuinely useful, but the trailing metadata block (Phase/cost/idempotency/Requires/Produces/Verify with/Safety/On failure) is dense boilerplate that partly restates the annotations and schema. Slightly over-stuffed but well ordered.

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 mutating, non-idempotent tool with no output schema, the description covers prerequisites (cache library), failure semantics, mutation warning, and the return contract { ok } / { error }, so an agent has everything needed to invoke and interpret it.

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 all three parameters (instancePath, threadContext, timeoutMs) are already documented in the schema, including the 'return <expression>' evaluation. The description's signature recap and loadstring note add no meaning beyond that, 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?

States a precise verb+resource: invalidating the executor's cached reference to a single Instance via cache.invalidate(inst), and clarifies the effect (next index returns a FRESH reference). This is functionally distinct from the other cache-* siblings (cache-is-cached, cache-replace) and an agent can tell what it does without opening the 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?

Gives clear use cases ('de-syncing a server-trusted object so your subsequent edits go unnoticed', 'forcing the executor to re-wrap a part you have been tampering with') plus prerequisites and verification guidance. It does not, however, explicitly name or exclude alternatives such as cache-replace or cache-is-cached, so the when-vs-which guidance is incomplete.

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