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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description adds substantial context beyond them: it boots into AROS, no copyrighted Kickstart ROM is involved, a public-domain game is already running, there is no configuration or state to manage, and on unsupported hosts it degrades to a text message. That last point is a real failure-mode disclosure an agent cannot get from annotations.

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?

Four sentences, front-loaded with the core action and constraint, and each carries distinct information (capability, environment, no-arg nature, fallback behavior). The clause 'This is a fixed, self-contained retro-computing demo' slightly restates the following 'nothing to configure' clause, so it is a touch redundant but not wasteful.

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 zero-parameter tool with no output schema, the description covers what it does, what it renders, what the caller must not supply, and what happens when the host cannot render it. Nothing an agent needs in order to decide whether to call it 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?

With zero parameters the baseline is 4, and the description reinforces it by stating 'there is nothing to configure and no arguments to give it,' which prevents an agent from hunting for optional arguments. It adds no field-level meaning beyond that, but there is none to add.

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: 'Open a real, cycle-exact Amiga 500 emulator in-chat.' It immediately qualifies the scope with '(MCP Apps hosts only)', and names the concrete environment (AROS) and preloaded content, so an agent knows exactly what this tool produces 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?

It gives an explicit trigger — 'call it when someone wants to see or play with a real emulated Amiga' — and an explicit exclusion, hosts without MCP Apps support where it only returns text. No alternative tool is named, but no sibling in the list appears to offer comparable emulator behavior, so the guidance is effectively complete rather than deficient.

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