Read a record

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

Goes well beyond the annotations (which already cover read-only, idempotent, open-world): it explains that identifiers may contain slashes, that 'date' only carries supported precision while 'date_code' appears with null date/year, and that 'next_offset' signals pagination. These are non-obvious data-shape behaviors an agent could not infer from the safety hints.

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?

Front-loaded with purpose and the identifier-format caveat, then the pagination rule last, which is the right ordering. The middle stretch enumerating sections is dense and slightly longer than needed, but every sentence carries 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 an output schema present, return values need not be explained, and pagination plus section costs are covered. The remaining gap is the section-name mismatch with the enum, which leaves the agent uncertain about which section keys are actually valid.

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 100%, so the baseline is 3, and the description genuinely enriches 'sections' and the offset loop. However, it describes sections named 'date', 'date_stated' and 'date_code' that are not in the schema enum (which only allows basic, citations, resources, full_metadata), so an agent following the prose could pass an invalid value and get a validation error.

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?

States a specific verb and resource ('Read one Library of Congress record by its identifier') and immediately ties it to the sibling tools that produce identifiers ('as returned by search_items or search_newspapers'). An agent can tell it apart from the search_* siblings without opening a schema.

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?

Clear usage context: this is the follow-up call after a search returns an identifier, and 'full_metadata' is flagged as 'large and rarely needed', which steers section choice. It stops short of explicit when-not guidance or naming list_collections as an alternative path.

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