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

Annotations say readOnlyHint=false, indicating a state-changing operation, and the description is transparent about the subscription side effect. It discloses that email destination is forced to the bound address, that webhook requires Pro, that destination is ignored for email, and the bind_email prerequisite — all beyond what annotations express. No contradiction with the 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?

Front-loaded with the core purpose in the first sentence, then layered details (tiers, prerequisite, examples, exclusion). Every sentence earns its place, though it is dense and slightly long; the information density justifies the 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?

Covers purpose, tier constraints, prerequisite, parameter guidance, a try example, and the read-vs-subscribe distinction. An output schema exists so return values needn't be explained. Minor omissions only: how to unsubscribe/list alerts and what the webhook payload looks like.

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 coverage is 100%, so params are already documented; the description adds tier semantics (email=free, webhook=Pro), clarifies that destination is ignored for email, and provides a working example showing valid slugs and a webhook URL. It reinforces but doesn't fully replace the schema — hence above baseline but not a 5.

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?

Opens with a specific verb+resource: 'Subscribe to movement alerts for a DCPI market' and states exactly what triggers a notification (Excess-Power / Constraint score moves). It explicitly differentiates itself from get_market_dcpi_rank by saying 'Do NOT use to read a market right now... this SUBSCRIBES to future movement', and the sibling context makes it distinct from set_site_alert/set_shortlist_alert.

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?

Explicitly names the alternative tool (get_market_dcpi_rank) and the condition that selects between them (read now vs subscribe to future movement). It also states the prerequisite (call bind_email first for email delivery), gives natural-language triggers ('tell me when this market moves'), a concrete try example, and tier conditions for email vs webhook.

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