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

Annotations already establish that this is read-only, idempotent, and non-destructive, so the description does not need to repeat that. It adds that the result is a list of chains/chain IDs, but does not describe the output structure, ordering, or any other behavioral nuance. Given the simple zero-parameter nature, this is reasonable, but it adds only minimal behavioral context beyond annotations.

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 a single sentence with no filler. It front-loads the verb and resource, and every word adds value. This is an example of appropriately concise specification.

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?

For a tool with no parameters, no output schema, and a trivially simple purpose, the description is complete. An agent knows exactly what action to perform and what information to expect. No additional context is necessary to invoke this tool correctly.

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 input schema has zero properties, so there are no parameters to document. The baseline for no parameters is 4, and the description correctly avoids inventing parameter details. It focuses on the output, which is appropriate here.

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 states a specific verb ('Get') and a precise resource ('list of chains / chain IDs supported by the API'). It clearly distinguishes this from sibling tools, which focus on individual assets or transactions, making the tool's scope unmistakable.

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 the usage context: call this when you need to know which chains or chain IDs the API supports. However, it does not explicitly state when to use it versus alternatives, nor does it mention any exclusions. For a tool with no overlapping siblings, the implied guidance is adequate but not explicit.

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