update_thread_fields

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

Discloses key allowlisting, rejection of unknown keys, auto-detection of field type, and provides example keys. Lacks details on whether updates are additive or replace existing fields.

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 concise sentences, front-loaded with purpose, no redundant 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?

Adequate for a batch update tool; covers key constraints and type behavior. Lacks return value or error handling details, but output schema is absent.

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?

Adds value beyond schema by explaining allowed keys, auto-detection mechanism, and example values. Schema already covers parameters fully.

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?

Clearly states 'Set or update multiple custom fields on a thread in one call,' with a specific verb and resource, and distinguishes from sibling tools like 'upsert_thread_field'.

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?

Implies batch usage by mentioning 'multiple custom fields in one call,' but lacks explicit guidance on when to use this tool vs. alternatives like 'upsert_thread_field' or prerequisites.

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