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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, and the description still adds real value on top: it enumerates what the response contains (purpose, concepts, adjustable parameters, expected outcomes, prerequisite stage, related lessons, canonical URL, usage steps) and disclaims the ability to execute the simulation. That is the kind of expectation-setting the annotations cannot carry.

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?

Two sentences, front-loaded with the core action and identifier source, with the usage directive last. The first sentence is a long enumeration of return fields, but each item is informative rather than 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?

There is no output schema, so the description must carry the return-value burden, and it does by listing the fields and the site-usage steps. Combined with a fully documented input schema and clear read-only annotations, an agent has everything needed to call and interpret this tool.

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 both parameters are already fully documented, including the stage-slug/stage-number acceptance and the locale fallback list. The description only restates the slug flexibility the schema already states and never mentions the language parameter, so it adds no meaning beyond the structured fields.

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 and resource ("Describe one MasterAI Now simulation") and immediately anchors it to the sibling that produces the identifier ("by its key from get_simulations"). This cleanly separates it from the list-style get_simulations and from unrelated siblings like generate_quiz or search_content.

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 a concrete usage trigger ("Use it before recommending a specific playground") and a scope exclusion ("it cannot run the simulation and does not claim to"). It does not explicitly say when to prefer get_simulations instead, but naming it as the key source makes the ordering implicit.

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