search_isrctn

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

Discloses read-only operation, no authentication required, result limits (up to 10), relevance filtering, and empty response message. With no annotations provided, description carries full burden and does well.

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?

4 sentences covering purpose, behavior, complementary role, and usage hints. Front-loaded and no unnecessary words, though could be slightly more concise.

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?

Covers purpose, usage, behavior, and limitations. With an output schema present, return values are presumably documented elsewhere. Sufficient for a moderate-complexity search tool.

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 has 100% description coverage, so baseline is 3. Description adds minimal extra meaning (e.g., 'filtered for relevance'), but mostly restates schema info like max results limit.

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 the tool searches the ISRCTN registry for UK and European clinical trials, distinguishing itself from sibling tools like search_clinical_trials by explicitly noting it complements ClinicalTrials.gov coverage.

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?

Provides explicit use cases: UK/European trials, academic studies, international coverage beyond ClinicalTrials.gov. Implicitly suggests alternatives by noting it complements other registries, though does not explicitly state when not to use.

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