mimicus_open_reference

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

Annotations already declare openWorldHint=true, non-readOnly, non-idempotent, non-destructive. The description adds meaningful context beyond them: the session is an isolated temporary Chromium instance, the return is an actual screenshot as image content, and additional resource origins require approval. It still doesn't explain session lifetime or how the session is torn down.

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 tightly written sentences with the core action front-loaded and the input constraint following. No filler, though the approval note is slightly compressed and could be clearer.

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?

The output schema covers return values and annotations cover the safety profile, so those burdens are lifted. However, for an 8-parameter tool with nested viewport objects and 0% schema coverage, the description omits too many parameters to be fully complete for correct invocation.

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% across 8 parameters, so the description must carry the full semantic load. It only implicitly covers url, the reference pair (referenceId/referenceUrl), and resourceOrigins; viewport, reducedMotion, operationId, and the meaning of the required 'authorized' flag are left completely undocumented. Significant compensation gap.

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 (open) plus resource (an authorized original site) and the concrete outcome (return its actual screenshot as MCP image content), which is more than a restatement of the name. It does not, however, explicitly distinguish itself from close siblings like mimicus_capture_view or mimicus_get_reference, so an agent must infer the boundary.

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?

The phrase 'Supply either a live reference pair or an explicit original URL' gives implicit conditions for calling (you need a reference pair or a URL). But it never states when to prefer this tool over mimicus_capture_view / mimicus_get_reference, and there are no explicit exclusions. Usage is implied rather than directed.

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