fetch_online_metadata

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

With no annotations, the description carries full burden but fails to disclose important behaviors. It does not mention that applying metadata (via apply_to_book_id) is a write/destructive operation, or that it requires network access. The return format (OPF) is mentioned but not elaborated.

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 two sentences with no waste. It front-loads the primary action ('Looks up metadata') and efficiently covers both the lookup and optional apply behavior. Every sentence adds value.

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 5 parameters, no output schema, and no annotations, the description covers the core functionality but leaves gaps. It does not address how multiple matches are handled, whether apply_to_book_id requires an existing book, or error behavior. The tool's full complexity is not fully described.

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 coverage is 40%, so the description must compensate. It explains that title, authors, and isbn are search criteria, which adds context beyond the schema. However, it omits details like expected formats (e.g., comma-separated authors) and does not improve descriptions for apply_to_book_id and fetch_cover beyond what the schema already provides.

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's function: looking up metadata from online sources by title/author/ISBN and returning an OPF, with the optional ability to apply that metadata to a book. This specific verb+resource combination distinguishes it from siblings like 'get_book_metadata' (which retrieves existing metadata) and 'set_metadata' (which sets metadata manually).

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 implies when to use the tool (for fetching external metadata) but does not explicitly state when not to use it or compare it to alternatives. It lacks exclusions or guidance on prerequisites, such as requiring network access or handling cases where no metadata is found.

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