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

Beyond annotations (destructiveHint, readOnlyHint=false), description discloses that the tool spends a paid credit, extends the promotional window if already featured, and returns a message if credits are zero. This provides essential behavioral context not captured in structured fields.

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 sentences, each essential. Front-loaded with the core action. No redundant information. Efficiently covers all critical aspects.

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?

Given a single parameter, no output schema, but destructive side effects, the description is complete: it covers prerequisites (own listing), cost (one credit), effect (~14 days featured), edge cases (no credits, synced listings), and references sibling tools.

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%, but description adds value by clarifying that 'listing_id' should come from 'my_listings' and that synced listings (synced:true) are also promotable, which is not inferable from the schema alone.

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 clearly states the action ('Promote (feature)'), the resource ('one of the authenticated agent's OWN listings'), and the condition ('by spending ONE promotional credit'). It distinguishes from siblings like 'buy_promotional_credits' and 'my_listings' by specifying it acts on own listings and uses credits.

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 advises to confirm with the user before calling due to spending a credit, and directs to 'buy_promotional_credits' if no credits. Also specifies that 'listing_id' should come from 'my_listings', providing clear when-to-use and when-not-to-use guidance.

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