ab_compare

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

With no annotations, the description carries the full burden of behavioral disclosure, but it only says 'compare ... page by page.' It does not explain whether comparison uses screenshots, DOM snapshots, or visual diffs; whether it modifies anything; whether auth profiles are required; or what the output format is. Given parameters like threshold, max_images, and max_changed_ratio, the behavior is significantly under-described.

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 description is one sentence with no filler and front-loads the core action. The example is useful and compact. It loses a point because the brevity comes at the expense of necessary operational detail, but as a concise purpose statement it is well structured.

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?

This is a 9-parameter tool with no annotations, no output schema, and no parameter-level descriptions, yet the description contains only a single sentence. It omits expected outputs, threshold semantics, image limits, auth profile behavior, and how this differs from sibling comparison tools. The description is too incomplete to support reliable invocation by an agent.

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% and there are 9 parameters, so the description must compensate for the schema's lack of explanation. It only indirectly references the two base URLs via the example ports. None of pages, viewport, profile_a, profile_b, threshold, max_images, or max_changed_ratio are explained, leaving the agent without enough information to set them correctly.

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 states a specific action ('Compare two running servers') and a clear comparison granularity ('page by page'). The example of main branch on :8080 vs a worktree on :8091 clarifies the intended resource scope. It does not explicitly distinguish itself from sibling tools like compare_images or compare_sets, but the object being compared is clear enough.

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 example gives a concrete scenario that implies when the tool should be used: when two live servers need to be compared page by page. However, it does not state when to use this tool instead of alternatives such as compare_images, capture_set, or run_qa, nor does it mention exclusions or prerequisites like server accessibility.

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