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

Annotations already cover read-only, idempotent, non-destructive behavior. The description adds valuable context by stating 'no auth required' and listing the specific data fields returned (abstract, bioproject, sample count, etc.), which goes beyond the annotations. It also attributes the data source to EMBL-EBI MGnify, providing provenance.

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 two sentences, front-loaded with the primary action and resource, followed by a compact list of returned fields. The provenance and auth note are relevant and not redundant. It is slightly dense due to the enumerated fields but remains efficient and scannable.

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 an output schema present, the description does not need to explain return structure. It covers how to obtain the accession (via study_search), what the tool returns, and auth requirements. It does not discuss error handling or invalid accessions, but for a simple lookup with a single required parameter, the provided context is sufficient.

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 for the accession parameter is 100% with its own description, satisfying the baseline. The description adds an example value and explicitly links the parameter to the sibling search tool, which helps the agent construct a valid accession. This is meaningful added context beyond the schema.

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?

Description clearly states the tool's action: 'Get full detail for one MGnify study by its accession', with a specific resource (MGnify study) and example accession. It enumerates the returned fields, which distinguishes it from the sibling search tool (ebi-metagenomics.studies.search) that would be used to find studies rather than retrieve a known one.

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 implies usage context by specifying the input is an accession 'from ebi-metagenomics.study_search', guiding the agent to first search for studies before using this detail tool. It does not explicitly state exclusions or alternative tools, but the source reference and single-accession parameter make the intended workflow clear.

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