ncbi_list_databases

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

The annotations already declare readOnlyHint: true and openWorldHint: true, so the description doesn't need to restate that it's safe. However, the description adds only that it 'Returns a formatted list' with descriptions and example queries, which is content detail rather than behavioral context. It doesn't disclose any additional traits such as pagination, ordering, or rate limits, so it stays at baseline value.

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 concise sentences—one for purpose and one for return value—with no irrelevant details. The action is clear and the format of the response is front-loaded. Only essential information is included, meeting the highest standard.

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?

Given the tool has no parameters and no output schema, the description adequately covers its full behavior: it lists databases with descriptions and example queries, and it specifies that the result is a formatted list. A small gap is the lack of context on how this tool integrates as a prerequisite for other NCBI tools, but it is not necessary for basic use.

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?

The tool has zero parameters, and the schema coverage is 100% (vacuously). Per the rubric, zero parameters warrant a baseline of 4, and the description adds no parameter info since there is nothing to describe. This is appropriate and no points are lost.

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 a specific verb ('List') and resource ('all supported NCBI databases') with the added detail of including descriptions and example queries. This distinguishes it from sibling tools like ncbi_esearch or ncbi_efetch, which search or fetch data, making the purpose unambiguous.

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 this is a discovery tool (to see which databases are available), but it does not explicitly state when to use it versus the other NCBI tools or mention any exclusions/alternatives. This is a clear gap for a tool that would logically be used as a preliminary step before querying specific databases.

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