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

Annotations declare readOnlyHint=true and openWorldHint=false, so safety is already covered. The description adds valuable behavioral detail: it discloses the internal ranking/weighting process, the simulation loop, and the returned artifacts (runId, outcome, confidence, falsifier, reasoning path). No contradiction with readOnlyHint, though a mutation implication of 'runId' creation could be clarified.

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 action and target are front-loaded in the opening clause, and the next-step routing is cleanly placed at the end. The middle clause is a dense run-on list, but every element carries information about the simulation's outputs and process.

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?

There is no output schema, so the description carries the burden of describing returns — and it does so thoroughly (runId, modeled outcome, confidence, falsifier, reasoning path, reality request). Combined with 100% parameter coverage and annotations, the definition is nearly complete, missing only explicit permission or failure-mode context.

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 fully documents stage, cycles, ageBand, markers, and condition. The description adds no syntax or format detail for these parameters beyond the schema, so the 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 opens with a specific verb and resource ('RUN THE DIGITAL TWIN for a condition') and describes the mechanism (ranks registry-tested interventions, walks a treat/observe/re-treat loop). It clearly separates itself from siblings by naming the downstream tools (post_reality_request, claim_work).

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?

Explicit next-step routing is provided ('NEXT: post_reality_request to get it tested, or claim_work to take it further'), giving the agent concrete alternatives with conditions. It lacks an explicit 'use this instead of X when Y' exclusion statement for upstream context, but the downstream guidance is strong.

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