get_execute_js_result

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

With readOnlyHint=false, openWorldHint=true, and no idempotency guarantee, the description must carry the behavioral burden, and it delivers extensively: timeout bounds (0-120 seconds), retention limits (10 minutes, 512 records, capacity eviction), unknown/expired semantics, late_result with late_reply_age, reservation/release behavior, and encoding rules. None of this contradicts the annotations; the reservation language actually explains why the tool is not purely read-only.

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 text is a single unbroken ~200-word wall of dense, multi-clause sentences filled with jargon ('reservation_held describes that probe, not a prior mutation'). It is properly front-loaded — the purpose leads — and every sentence carries real facts, but the lack of any structural breaks makes the critical guidance costly for an agent to parse.

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 high complexity (async reservations, retries, late results, unpaired-UTF-16 handling, export failure) and the presence of an output schema, the description covers nearly everything an agent needs: when to call, timeout range, retention, retry semantics, late-result structure, and decode instructions. What keeps it from a 5 is pure structure, not missing information.

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 0%, so the description must compensate. It adds a concrete meaning to timeout ('timeout is 0-120 seconds') and clarifies that operation_id originates from execute_js or bridge commands, including the nested-vs-outer distinction. It doesn't state the operation_id format, but for a zero-coverage schema this is solid compensation.

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 opening phrase names a specific verb-resource pair — 'Read or wait for an operation_id' — and scopes it to execute_js or other timed-out bridge commands, which separates it from the sibling list at a glance. It even carves out the nested open_new_tab reconciliation case, so an agent knows exactly what this tool is for.

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?

There is explicit routing guidance: 'Call from the submitting MCP session' plus the exclusion 'The outer tab-creation ID uses open_new_tab recovery,' which tells the agent when not to use this tool and names the alternative. It doesn't enumerate all other alternatives, but it does resolve the two most likely confusion points (execute_js results and open_new_tab nested vs. outer IDs).

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