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

Annotations only declare openWorldHint=false and destructiveHint=false, so the description carries the real behavioral load and does so well: it discloses the matching rule (every keyword must appear in title or description), the quota, and the non-retroactive scope ('Only affects ads posted after the alert is created'). These are exactly the traits an agent cannot infer from 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?

Five tight sentences, front-loaded with the action and outcome, then constraints. The parenthetical use-case clause grounds the tool's audience without padding.

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 two-parameter creation tool with no output schema, the description covers purpose, matching logic, prerequisites, quota, and temporal scope. An agent has everything needed to decide and invoke correctly.

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 baseline is 3, but the description adds matching semantics beyond the schema: keywords are AND-combined and must appear in the ad title or description, and category acts as a filter. The enum list itself is left to the schema, which is appropriate.

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 ('Create an alert') and explains the triggering semantics: an email when a wanted ad matches keywords and/or category. This clearly distinguishes it from siblings like delete_alert, list_alerts, and search_wants.

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 the use context ('sellers who want to hear about demand'), the prerequisite ('Needs at least keywords or a category'), and the cap ('Up to 10 alerts per user'). It does not name an alternative tool for one-off searching, but the when-to-use condition is unambiguous.

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