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

Annotations already cover readOnly/idempotent/openWorld, so the bar is lower, and the description still adds real context: the call is 'Free', names are mutable and non-unique while signal_id is the stable identity, and the result is a full account-wide enumeration. It does not mention ordering, pagination, or size limits for accounts with many signals.

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?

Two short paragraphs, front-loaded with the resource and its return fields, followed by cost and identity caveats. No sentence is redundant against the schema or annotations.

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 summarizes them usefully. Combined with the free-call note and the signal_id-vs-name rule, an agent has what it needs to call and interpret this correctly; only filtering semantics for signal_type are left implicit.

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 0%, so the single signal_type parameter is documented nowhere but its enum literals. The description's phrase 'its type' and 'an account can have several of one type' hints that type matters for identity, but it never says that signal_type filters the listing or what an omitted value does (default null).

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 ('List the signal monitors on this account') and enumerates exactly what comes back: signal_id, name, type, tracked profiles, active/paused status. The closing lines separate it from the mutation siblings (create_signal / update_signal), so an agent can distinguish it without opening the schema.

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?

'Call this before creating or changing a signal' gives an explicit precondition that routes the agent away from create_signal/update_signal. It also warns never to identify a signal by name alone, which is actionable selection guidance. It stops short of naming a true alternative (e.g. list_signal_leads for per-signal results) or stating when this list is not needed.

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