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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and a closed world, so the safety profile is fully covered. The description usefully adds that the result set is a fixed twelve nodes with liveness and Agent Card data, which implies no pagination or filtering, but says nothing about ordering or failure modes.

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?

A single short sentence with no filler, and the key content (the twelve nodes and their attributes) is front-loaded. It reads as a fragment rather than a sentence, which slightly hurts clarity but not length.

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 zero-parameter, non-paginated read tool with no output schema, the description covers enough to know what comes back at a high level. However, undefined domain terms like 'market nodes', 'regional doors', and 'Agent Cards' are not explained, leaving the agent unsure what the returned data actually represents.

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 takes zero parameters, so there is nothing for the description to disambiguate. Baseline 4 applies since no parameter semantics are needed.

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 is a noun phrase rather than a verb+resource, and it largely restates the title 'List market nodes', but it does add real detail beyond it: exactly twelve nodes, liveness status, regional doors, and Agent Cards. The resources covered are identifiable, though nothing distinguishes this from sibling list 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?

There is no when-to-use, when-not-to-use, or alternative-tool guidance. The sibling tools (get_record, list_aliases, list_events_since, resolve_issuer) are never referenced, so the agent must infer from the name alone when this listing is the right call.

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