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

No annotations are provided, so the description must carry the full burden. It discloses the default return fields (SEARCH_TOOL_DEFAULTS) and max_studies default, offering some transparency about output. However, it does not describe API behavior such as how criteria are combined (AND/OR), error handling, or rate limits. For a read-only search tool, this is acceptable but leaves room for improvement.

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 well-structured with a clear one-sentence purpose followed by a bulleted parameter list. Every sentence adds necessary information, and the front-loaded purpose makes it easy to scan. No redundant or vague phrasing.

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?

For a search tool with 8 parameters and no output schema, the description covers the parameters, default behavior, and return fields. It does not explain how criteria are combined (e.g., AND vs OR) or pagination, but the essential information for invocation and interpretation is present. This is appropriate for the tool's complexity.

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. The description adds value by explaining the purpose of each parameter (conditions, interventions, sponsors, terms, nct_ids) and providing details not in the schema, such as the default max_studies being 50 and the exact list of default fields returned. This goes beyond the schema, warranting a 4.

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 'Search clinical trials using multiple criteria', which specifies the verb (search), resource (clinical trials), and scope (multiple criteria). The name 'search_trials_combined' and the list of sibling tools like search_trials_by_condition and search_trials_by_intervention make it evident that this tool is for combined multi-criteria searches, distinguishing it from single-criterion siblings.

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 explains that this tool allows combined search with multiple criteria, which implies it should be used when more than one search dimension is needed. It does not explicitly mention alternatives or when not to use it, but the 'combined' wording and sibling context provide clear guidance. The absence of exclusions keeps it from a 5.

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