rakuten-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions that keyword searches 'routes to BooksTotal,' which adds useful context about the search behavior. However, it doesn't describe important behavioral aspects like pagination, rate limits, authentication requirements, or what the response format looks like (especially critical since there's no output schema).

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 description is extremely concise with just two sentences, both of which earn their place. The first sentence states the core purpose, and the second provides crucial usage guidance about the keyword parameter. There's zero wasted text or redundancy.

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?

Given that there's no output schema and no annotations, the description should do more to explain what the tool returns and any behavioral constraints. While it's complete enough for a basic search tool with good parameter documentation, the lack of output information and behavioral context leaves gaps that could hinder an AI agent's understanding of how to properly use this tool.

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 documents all 5 parameters thoroughly. The description adds minimal value beyond the schema by mentioning that keyword searches 'routes to BooksTotal' and work 'across all book categories,' which provides some semantic context for the keyword parameter. This meets the baseline expectation when schema coverage is high.

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 specific action ('Search for books') and resource ('on Rakuten Books'), and distinguishes this tool from alternatives by mentioning 'For general keyword searches across all book categories, use keyword (routes to BooksTotal).' This provides clear differentiation from sibling tools like search_genres or search_products.

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 explicitly provides when-to-use guidance by stating 'For general keyword searches across all book categories, use keyword (routes to BooksTotal).' This gives clear context about when to use the keyword parameter versus other search fields, though it doesn't explicitly mention when to use this tool versus other sibling tools like search_genres.

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