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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond them: it requires a personal GtoPdb API key, supplies the registration URL, and describes what is returned. Rate limits and pagination behavior are not addressed.

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-loads the core action and data source before the auth prerequisite, and each sentence carries information. Slightly dense but no filler.

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 no output schema, the description usefully summarizes return contents and covers the critical auth prerequisite. Minor gaps around result volume/pagination exist but the limit parameter in the schema mitigates this.

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%, with both target_id and limit documented inline (including an example id). The description reinforces the origin of target_id and the _apiKey requirement but adds little syntactic detail beyond the schema, so the baseline of 3 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 (List) and resource (quantitative ligand interactions for a protein target) with the exact data source (Guide to PHARMACOLOGY / IUPHAR-BPS). It also enumerates the returned fields (interaction type, action, affinity like pKi/pIC50), which lets an agent distinguish it from the sibling ligand_interactions.

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?

Names the sibling search_targets as the source of the required target_id, giving clear context for when this tool is applicable. It stops short of explicitly stating when to prefer it over ligand_interactions or any exclusions.

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