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

Beyond the annotations (readOnly, idempotent, openWorld, non-destructive), the description discloses what sources are read ('each site's public home and pricing pages'), the billing model ($0.50 per call from Exepal credit), and the failure policy ('not charged when a site can't be read or the AI part fails'). That is materially useful behavior an agent cannot infer from the annotation set, and nothing contradicts the annotations.

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 definition is front-loaded with purpose, then usage, then behavior and cost, and every clause about reading pages and failure billing earns its place. It loses a point because the long enumerated return-shape list (summary, yourPitch, rivals[]…, platforms) restates what an output schema already provides, inflating the 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?

For a two-parameter, open-world report tool, the description covers trigger context, data sources, cost, and failure-charging behavior, which is everything an agent needs to decide and call correctly. The output schema already handles return values, so the extra enumeration is redundant rather than a completeness gap.

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% and both parameters carry inline examples ('myapp.com', '["rival.com", "other.io"]'), so the schema already does the heavy lifting. The description only echoes the constraint of 'up to 3 competitors' without adding format rules (e.g., scheme handling, subdomain treatment), which is the expected baseline-3 level.

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 opens with a concrete verb-plus-resource framing: it places 'a website next to up to 3 competitors' and enumerates the compared dimensions (headline, button, prices, free plan, proof, FAQ, integrations, comparison pages). It is clearly distinguishable from siblings like seo_report, seo_gap, or client_report, which an agent could otherwise confuse with a competitor analysis tool.

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?

It gives explicit triggering conditions: 'Use when a founder asks how their site compares with competitors, what rivals do better, or what to change on their landing or pricing page.' That is strong when-to-use guidance, but it never names an alternative tool or states when another sibling (e.g., seo_gap or seo_report) would be the better pick, so the routing is one-sided.

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