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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds one genuine behavioral detail — comparison_url only appears when a researched head-to-head page exists — but says nothing about parameter validation failure modes or rate limits, so it goes modestly beyond the annotations rather than richly.

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 tight sentences: the first front-loads what is compared and what the output contains, the second covers the conditional comparison_url. No filler or restated title content.

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 simple read-only two-parameter tool with full schema coverage and an output schema (so return values need not be explained), the description is essentially complete, and it helpfully details output content anyway. The only gap is the absent when-to-use guidance relative to list_alternatives.

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%, with both parameters documented as slugs including pattern and length constraints, so the schema carries the semantics. The description adds nothing about the slug format or whether order of a/b matters, so baseline 3 applies.

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+resource (compare two EffectHub tool cards) and enumerates the compared dimensions (pricing, scores, platforms, API, liveness) plus the plain-sentence diff. This is clearly distinguishable from the single-tool sibling get_tool and the listing siblings search_tools/list_alternatives.

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?

Usage is only implied: the agent can infer this is for head-to-head comparison of exactly two known tools. There is no explicit when-to-use, when-not-to-use, or routing statement against the similar-sounding sibling list_alternatives, so the agent must infer the boundary itself.

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