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

Annotations already disclose the tool is read-only, idempotent, and non-destructive. The description adds value by detailing the specific return fields and the 'pre-calculated' nature of the timing, which is behavioral context beyond the annotations. It does not mention any caveats or response format details, but the strong annotation coverage lowers the bar.

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?

Two sentences, front-loaded with the core purpose and followed by a directive about the alternative. Every word contributes; no redundant or filler content.

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?

Even without an output schema, the description enumerates the key returned values (progress percentage, slots remaining, estimated end time), making the tool's output clear. The strong annotations cover safety context, and the tool's simplicity means no further details are essential.

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, so the baseline is 4. The description correctly adds no parameter-specific guidance since none exist, and the schema coverage is trivially 100%.

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 the tool's function: retrieving current Solana epoch timing, specifying the exact data fields (progress percentage, slots remaining, estimated epoch end time). It also explicitly contrasts with Solana RPC getEpochInfo, making its purpose distinct from external alternatives and sibling tools.

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 provides explicit guidance: 'Use this instead of Solana RPC getEpochInfo', with a clear reason ('returns pre-calculated timing with estimated end date'). This directly tells the agent when to choose this tool over a known alternative, satisfying the when-to-use criterion.

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