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

Adds real behavior beyond the annotations: it explains the user-visible effect (stories return to the feed) and the idempotency semantics (unmuting a non-muted publication changes nothing), which clarifies rather than repeats the idempotentHint. It doesn't cover scope limits such as whether re-enabling affects historical stories or per-device state, but a 4 is fair given annotations already declare non-destructive, non-open-world behavior.

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?

Four short sentences, each doing a distinct job: define the action, direct to the discovery tool, route to the alternative, then disclose idempotency. Nothing is redundant or buried.

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 single-parameter, non-destructive toggle with full schema coverage and no output schema, the description covers purpose, discovery, alternative routing, and idempotent behavior. Nothing an agent needs to call it correctly is missing.

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 the baseline is 3, but the description adds a meaningful constraint the schema does not: the name must be the same exact name used to mute, implying exact-match lookup rather than fuzzy resolution. Small but genuine added value.

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 ("Unmute a built-in publication") and immediately names its inverse (disable_global_source) plus the outcome ("Stories return to this account's feed"). The distinction from toggle_source for custom RSS feeds is made explicit, so an agent can separate it from siblings without reading any 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?

Gives when-to-use (unmute something previously muted), when-not-to-use (custom RSS feeds go to toggle_source), and where to find candidates (list_sources shows muted ones). All three routing cues an agent needs are present.

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