install_browser

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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, so the agent knows this is a network-touching mutation. The description adds genuinely new context: the ~150 MB download size, that it runs asynchronously in the background, and that progress must be polled via session_status. It does not say what happens on failure or whether re-running is safe, which keeps it from a 5.

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?

Three short sentences, each carrying distinct information: what it installs and its cost, that it is async and where to check progress, and the precondition. Front-loaded with the action and zero 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?

For a zero-param, no-output-schema installer, the description covers the important operational facts: size, async behavior, progress-check mechanism, and when it is needed. Failure/retry behavior and whether login is blocked during install are the only notable omissions.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. The description correctly implies no input is required, and no parameter-level meaning is missing.

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 ("Descarga e instala el navegador") and immediately identifies which browser (Chromium, ~150 MB) and why the MCP needs it (for login). An agent can distinguish this from sibling install/setup tools and from session_status without opening any 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 an explicit precondition — "Solo hace falta si session_status indica que falta" — which is effectively both the when-to-use and the when-not-to-use rule. It also names the sibling tool (session_status) that gates the decision, leaving nothing to inference.

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