get_collection_fields

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds a non-obvious behavioral fact that annotations don't cover: it 'Works without a token,' which tells the agent no auth is needed. It doesn't describe return structure in depth, but with annotations covering the safety profile this is solid.

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 the core action, and the code examples plus the 'read before interpreting' guidance each earn their place. Slightly long across four short paragraphs, but nothing is redundant.

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?

No output schema exists, yet the description explains exactly what the tool returns (a code-to-label dictionary) and why the agent would need it. Combined with the schema's parameter documentation, an agent has everything required to call it correctly.

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%, and the schema itself documents collection_id with an example ('1417683' for the 1880 US census) and a pointer to search_collections. The description only conceptually frames what a collection is, so the baseline 3 for high-coverage schemas applies.

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 ('Decode') and resource ('the field codes a collection's indexed records use'), then concretely illustrates the codes with examples like PR_FTHR_NAME and their decoded meanings. An agent can immediately distinguish this from get_collection or get_record.

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?

Explicitly says 'Read it before interpreting a record from a collection you have not worked with,' which names the trigger condition. It also points to search_collections for finding the collection id, connecting to the sibling that supplies the input.

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