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

With no annotations, the description carries the full burden. It does disclose the compared data points and the fact that an smm.guide comparison page is involved, which is useful output context, but says nothing about authentication needs, rate limits, failure behavior for unknown slugs, or whether the call is a pure read.

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?

One front-loaded sentence with the cardinality first and the input requirement last. The attribute enumeration is long but earns its place since there is no output schema, though the em-dash list is slightly dense.

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 one-parameter tool with full schema coverage and no output schema, the description covers the cardinality constraint (matching minItems/maxItems), the accepted identifier formats, and the returned fields, which substitutes well for a missing output schema. Only edge-case/error behavior is absent.

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 the single parameter is already documented as 'Slugs (prm4u-com) or domains (prm4u.com)'. The description's 'Pass slugs or domains' merely restates the schema, 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 (compare) and resource (panels) with an explicit cardinality ('Two to five panels side by side') and enumerates the exact attributes compared. This makes it clearly distinguishable from the single-panel get_panel and the retrieval-oriented search_panels siblings.

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?

'Pass slugs or domains' gives input guidance, and the cardinality implies the compare-multiple use case, but there is no explicit when-to-use/when-not guidance or named alternative such as get_panel for a single panel. Usage is only implied.

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