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

Annotations already cover the read-only (readOnlyHint) and open-world (openWorldHint) profiles. The description adds useful context beyond that: the tool returns resolved handles and endpoints, and the relay aggregates third-party/regional labelers, which corroborates the open-world hint. It does not discuss pagination or ordering, but the schema handles paging.

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?

Front-loaded with the primary action and return contents, then the workflow relationship. Two sentences that each earn their place. Minor typographical run-on ('relay,each') is the only flaw.

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?

An output schema exists so return values need not be spelled out, yet the description still names the key fields. Combined with explicit routing to query_labels and annotation-covered safety, an agent has everything needed to call this correctly; only paging behavior is left entirely to the schema.

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 description coverage is 100%, so limit and cursor are already fully documented in the schema (including the cursor-chaining instruction). The description adds no parameter meaning beyond that, so the baseline 3 applies.

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?

Specific verb+resource: 'List the labeler (moderation) services known to the labeler relay' and it enumerates the returned fields (DID, resolved handle, service endpoint). It explicitly distinguishes itself from the sibling query_labels, which is the main confusion risk in this namespace.

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?

States the sequencing rule outright: this is 'the discovery step BEFORE query_labels, which needs a labeler DID/handle up front.' It also names the concrete instances an agent would want (moderation.bsky.app and third-party/regional labelers) and the hand-off ('pass one to query_labels').

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