download_structure_file

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

With no annotations, the description carries the full burden of behavioral disclosure. It states that the tool downloads a file and returns a JSON string with status and file path, and it explains the output_dir and filename parameters, implying file system writes. It does not mention potential side effects like overwriting existing files or network requirements, but these are reasonable assumptions for a download tool. The description is not contradictory and provides adequate transparency for safe invocation.

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 structured as a clear docstring with Args and Returns sections. It is not overly verbose, and each sentence provides necessary information. The main purpose is front-loaded, and the parameter details are organized logically. While it is longer than a one-liner, the detail is justified for the tool's functionality.

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?

The description covers all parameters, provides return information, and explains file format options. It is complete for a download tool, and the existence of an output schema (not shown here) further reduces the need to describe return values in detail. It does not cover error handling or network prerequisites, but these are not essential for correct invocation.

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 description comprehensively documents all four parameters in the Args section, exceeding the bare schema. It explains pdb_id as a 4-character PDB identifier with an example, enumerates all file_format options with defaults, and clarifies output_dir and filename defaults. Since schema coverage is 0%, the description fully compensates, adding significant meaning beyond the schema.

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 purpose: 'Download a structure file from RCSB PDB.' This is a specific verb (download), resource (structure file), and source (RCSB PDB). It distinguishes from sibling tools like get_pdb_entry, which retrieve entry metadata, and query_rcsb_api, which performs API queries, by focusing on file download.

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 does not explicitly state when to use this tool versus alternatives, nor does it mention exclusions or conditions. However, the purpose is self-evident for downloading structure files, and the existence of siblings for different tasks makes the usage context implicit. There is no misleading guidance, but the lack of explicit routing to alternatives is a gap.

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