Subscribe Events

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

With no annotations, the description carries the full burden and does so well: it discloses idempotency, the stdio persistent-session prerequisite, the notification channel (logger="events"), the payload shape with concrete keys, and the catch-up semantics on reconnect. That is exactly the mutation/side-effect context annotations would otherwise supply.

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 action, then timing, payload, and reconnect semantics, with essentially no filler. Minor deduction because the hard prerequisite ('Requires a persistent session (stdio)') is buried in the final line rather than surfaced early where a failure would be caught.

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?

Covers everything an agent needs for a zero-param subscription tool: when to call, what arrives asynchronously, the payload contract, and the environment constraint. The output schema plus the described push payload leave no ambiguity about return behavior.

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 and the baseline applies. It does not need to compensate for any schema gap 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?

States a specific verb and resource ('Register this session for server-push download events'), which cleanly separates it from the polling-style siblings such as download_status, list_downloads and download_programme. An agent can tell this is a subscription/registration call rather than a query.

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?

Gives explicit timing ('Call once after connecting', 'again after reconnecting') and reassures that repeat calls are harmless. It stops short of naming an alternative or a when-not-to-use condition, e.g. it never says whether this replaces or complements polling via download_status.

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