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

Annotations already cover the read-only safety profile, and the description adds substantial extra context: SP+SB coverage with a program label, the own_target self-exact/self-phrase rows that stage_negatives refuses, and the attribution-driven default window ending 3 days back. These are non-obvious operational constraints an agent could not infer.

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?

Front-loaded with the purpose and return shape, followed by progressively finer caveats; each clause earns its place. Slightly dense with parentheticals, but nothing is redundant.

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 14-param, no-output-schema tool it covers the decision-critical edge cases (own_target exclusion, SB labeling, attribution window). It omits nothing blocking, though it says little about pagination or result ordering beyond what the schema notes.

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 71%, so the schema documents most params; the description adds meaning beyond it by explaining why end_date exists (override the 3-day attribution window) and by describing the campaign_type=SB routing used with stage_negatives. Other params (sku/asin/parent/limit/offset) are left to the schema, which is acceptable at this coverage.

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+resource+scope: 'Find non-converting search terms with significant spend — candidates for negative keyword addition,' then sharpens it with 'high clicks/spend but zero orders.' This distinguishes it from siblings like ppc_search_terms, ppc_harvesting_candidates, and ppc_negatives without the agent needing to open a 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?

Clear when-to-use (negative keyword candidates) and a downstream handoff (stage_negatives), plus an explicit exclusion: never negate own_target rows, pause/lower bid instead. It does not name the opposing sibling (e.g., ppc_harvesting_candidates for converting terms) to route the agent, so it stops short of full alternative-routing.

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