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

Annotations already declare readOnly, idempotent and openWorld, so the safety profile is covered. The description adds genuinely useful behavioral detail the annotations cannot carry: the return is per-plan pricing plus licence status, and each named provider must be linked with links.getStarted copied exactly including the ?ref= segment, which opens the intake with the coupon applied. It says nothing about latency, caching, partial failures if one provider name is unresolvable, or rate limits.

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?

Front-loaded with the resource and a tight list of what is returned, then the usage condition, then the linking rule -- a sensible order. The first sentence is a very long comma-run and the ?ref= instruction is verbose, but almost nothing is padding; each clause conveys a distinct contract about the output.

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?

No output schema exists, and the description compensates well by describing the returned fields and the exact URL form to surface. For a six-parameter, open-world comparison tool it leaves only minor gaps: no statement of failure behavior for unknown provider names, and no explicit hand-off to single-provider or referral-link siblings for follow-up steps.

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 100%, so the schema already explains drug, state, dosage_mg, plan_type, providers and currently_taking_glp1 with their enums and defaults. The description only reinforces dosage_mg ('like for like' pricing) and never mentions state or currently_taking_glp1, which the schema argues are the two easiest to omit. Baseline 3 is the right ceiling when the schema carries the load.

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 names the resource precisely (two to four providers side by side) and enumerates the exact comparison dimensions the tool returns: price at a dose/plan, ratings movement, review-share breakdowns, email response speed, pharmacy licence status, features and a Get Started link. An agent can distinguish this from the sibling listing/search tools purely from the text, and the fragment 'Use for "X or Y?" questions' pins the intent.

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 a clear selecting condition ('Use for "X or Y?" questions') and a concrete precondition for comparable output ('Pass drug and dosage_mg so the prices are like for like'). It also rules out a misuse mode (do not link learnMore, another GLP Winner page, or the provider's own site). It stops short of naming a sibling alternative such as a single-provider lookup for non-comparative questions, so it is strong but not exhaustive.

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