ddb_read_book

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

With readOnlyHint=true, the safety profile is already established. The description adds valuable context about the login requirement (run ddb_login first) and the automatic title resolution against the library. No contradiction with 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?

Two sentences carry all necessary information: the first states the core purpose and input flexibility; the second lists optional parameters and the login prerequisite. No filler 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?

Despite having no output schema, the description sufficiently covers the tool's behavior: what it reads, accepted inputs, optional chapter/heading/char limit controls, and authentication requirement. For a read-only tool with well-documented parameters, this is ample context.

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 baseline is 3. The tool description mostly restates the schema's parameter explanations (e.g., slug/title flexibility, max_chars) without adding new meaning or clarifying relationships between parameters.

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 starts with 'Read a D&D Beyond book', a specific verb and resource that clearly distinguishes it from sibling search/list tools (e.g., ddb_search_spells, ddb_list_library). It further clarifies scope by noting options for chapters, headings, and response size control.

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 provides clear context on when to use it (reading a book), input flexibility (slug or title resolved automatically), and critical prerequisite (login). However, it does not explicitly mention alternatives or when not to use it, such as preferring a search tool for specific content.

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