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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by explaining that quartile and indexing are available for any caller, while trust score and APC are only for an identified (likely previously indexed) journal. This is useful behavioral context beyond the annotations, though it does not detail response structure or error conditions.

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?

A single, front-loaded sentence that efficiently conveys the core function and key supporting details. No filler or redundant wording. Every clause ('side-by-side', '2-4', 'by ISSN', the attribute lists) contributes essential information.

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, the description carries the burden of indicating what the caller can expect. It mentions the compared attributes (quartile, indexing, trust score, APC), giving a partial picture of the return content. However, it does not explicitly state the output format (e.g., JSON object, array). Given the tool's simplicity (one param) and the clarity of the description, it is largely sufficient.

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?

The input schema already fully describes the 'issns' parameter (2-4 ISSNs to compare with an example). The description reinforces this with '2-4 journals by ISSN' but does not add new semantic details about the parameter beyond what the schema provides. Baseline for 100% schema coverage is 3, and the description only mildly reinforces rather than complements.

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 clearly states the tool performs a side-by-side comparison of 2-4 journals by ISSN, listing specific attributes (quartile, indexing, trust score, APC). This distinguishes it from sibling tools like get_journal (single journal) and search_journals (search). The verb is implicit in 'comparison' but the resource and scope are unambiguous.

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?

The description implicitly indicates when to use the tool: when comparing multiple journals side-by-side. It does not explicitly mention alternatives or exclusions, but the context is clear. The phrase 'for any caller' vs 'for an identified one' gives hints about data availability, which aids in selective usage.

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