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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds one piece of behavioral context beyond the annotations: the result is a side-by-side comparison plus a comparison page URL, which tells the agent something about the shape of the response. It says nothing about rate limits, auth needs, or error behavior, but with annotations present the bar is lower.

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?

It is a single short fragment with no wasted words and the key concept front-loaded, which is good. But the terseness crosses into under-specification, and the '+' abbreviation is informal for a tool description.

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?

With no output schema, 0% parameter coverage, and only a single annotation, the description should explain argument format and confirm what comes back. It gestures at the return value but leaves the argument semantics an agent needs to actually invoke the tool unspecified.

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%, so the description must carry the burden for a, b, and verbose. It only weakly maps 'two tools' onto the a/b pair and leaves the accepted format ambiguous (tool name, slug, or id), while 'verbose' is never mentioned at all. This is insufficient for three undocumented parameters.

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 fragment 'Side-by-side of two tools + comparison page url' conveys the resource (two tools) and the deliverable (a comparison view plus URL), so the core purpose is inferable. However, it is a noun phrase with no verb, and it does not differentiate itself from siblings like list_alternatives or recommend_tools, which an agent could easily confuse with a comparison operation.

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?

There is no explicit when-to-use guidance and no named alternative. The only implied condition is that the caller has two tools to compare, which the argument names (a/b) already suggest. Nothing tells the agent when to prefer this over list_alternatives or recommend_tools.

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