Update project defaults

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

Annotations provide readOnlyHint=false, destructiveHint=false, so the mutation aspect is already implied. The description adds valuable behavioral detail: 'schedule is replaced as a whole: omitted schedule fields reset to their defaults (jitter 60, timezone UTC, no cron)' — this is a crucial side effect not visible in schema or annotations. This warning about destructive replacement goes beyond the annotations.

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?

Three sentences, all content-bearing. The first names the resources, the second warns about the destructive whole-replacement behavior, the third gives pairing/lookup guidance. No fluff. Could arguably be more compact but the density of information justifies the length.

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 tool with 11 params, no output schema, and moderate annotation support, the description covers the critical ambiguities: schedule replacement semantics, SERP market movement pairing, and lookup guidance. It doesn't fully document return values (no output schema exists) and doesn't enumerate each parameter, but covers the highest-risk behaviors. Reasonably complete for complexity.

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 only 45%, so the description must compensate. The description explains the semantics of the schedule fields (jitter default 60, timezone UTC, cron) and the pairing rule for country/device vs location_key. It clarifies the idempotency dimension, frequency enums, and location_key pattern. It doesn't document every parameter individually, but for 11 params with 45% coverage this meaningfully compensates.

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 states the specific verb+resource (update project default rank-check schedule and SERP market) and clearly differentiates from siblings like get_project_defaults (read counterpart), update_project (broader project settings), and search_locations (lookup helper). It names two distinct update areas and how to move the SERP market.

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?

Description explicitly instructs to provide country and device together OR use a location_key, and to use search_locations and pass its location_key verbatim — clear when-to-use guidance. It doesn't explicitly name alternatives/siblings or state when NOT to use this tool, but the usage context is clearly conveyed.

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