Node Pubsub

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

Annotations already establish read-only, idempotent, non-destructive, open-world behavior, so the bar is lower, yet the description still adds real value: it guarantees no message payloads are retrieved and explains that cluster mode aggregates shard primaries. Those are behavioral facts an agent could not derive from the annotations or schema. Missing only cost/latency expectations for the concurrent shard probes.

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?

Three short clauses, front-loaded with the resource and the signal set, then the crucial 'counts only' constraint, then cluster behavior. No filler, no restatement of the tool name, and the most decision-relevant caveat is placed before the mode note.

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 shape need not be explained, and all four parameters are fully covered by the schema. The description supplies the non-obvious operational facts (no message contents, cluster aggregation). The one gap is routing guidance relative to sibling node_* diagnostics, which a more complete definition would include.

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%, with each of the four parameters already documented including defaults and bounds. The description adds no parameter-specific meaning beyond that, aside from loosely implying that 'pattern' maps to PUBSUB CHANNELS filtering and that 'top' controls the ranked channel list. Baseline 3 applies when the schema carries the parameter burden.

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 names the resource precisely (Pub/Sub) and enumerates the specific signals returned: channel and pattern counts, top channels by subscriber count, and subscribers with large output buffers. That is far more specific than the bare name 'node_pubsub'. It does not explicitly contrast itself with sibling diagnostics like node_clients or node_info, which keeps it from a 5.

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?

Framing it as 'Pub/Sub pressure' implies a diagnostic use case, and 'Counts only, never messages' scopes what it will and won't answer. However, there is no explicit when-to-use statement, no named alternative for related questions (e.g. inspecting actual Pub/Sub clients), and no stated prerequisites. Usage is inferable rather than directed.

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