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

The annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the description's job is smaller. The '(untrusted text)' marker is genuinely valuable: it warns the agent that returned signal content may contain injected instructions, which no annotation conveys. It does not say whether a dismissal is reversible or what happens when dismissing an already-dismissed signal.

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?

A single front-loaded sentence covering both modes with no filler. The parenthetical warning is placed mid-sentence rather than at the end, which slightly interrupts the read but is defensible given its importance.

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?

For a mutating tool with zero schema description coverage and no output schema, the description leaves too much open: idempotency_key semantics, workspace scoping, what a dismissal affects, and what the list response looks like are all undocumented. The untrusted-text warning is the only real depth it adds.

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 description must compensate; it partially does by clarifying that 'one, several' means passing a signals list and 'all' means a bulk mode, which sheds light on the action enum. It says nothing about the workspace parameter, the idempotency_key, or the 20-item cap on signals.

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 specific resource (open competitor signals) and the two operations the tool performs (list or dismiss). This distinguishes it from the ads/scans siblings, though it does not explicitly say how it relates to competitor_ads_list or competitor_scans_list.

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?

The phrase 'or dismiss one, several or all' maps usage to the action enum, so a reader can infer when to select each mode. There is no explicit when-not guidance, no mention of prerequisites (e.g., needing signals from a prior list call), and no reference to alternative tools.

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