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

Annotations already declare destructiveHint=true and idempotentHint=true, but the description adds behavioral specifics not in the annotations: null clears fields, projectIds replaces the linked set, and an empty array unlinks all. It also discloses the ownership/permission requirement. Return/pagination behavior is not described, keeping it out of the top tier.

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 core action and then a single dense field list where each entry carries invocation-relevant content. Some redundancy with the schema prevents a 5, but there is little wasted prose.

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 7-parameter mutation with no output schema, the description covers partial-update semantics, null-clearing, replacement behavior, and the auth requirement. It does not describe the response shape, but with no output schema that is an acceptable gap.

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 86%, so the schema already documents the parameters and enum values, establishing the baseline of 3. The description largely restates those fields; its only genuine addition is 'pass empty array to unlink all' for projectIds, which is a modest increment over the schema.

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 ('Partially update one goal') and the partial-update semantics, so an agent can distinguish it from create_goal or update_key_result_value without opening the schema. It stops short of explicitly naming or contrasting a sibling, so it does not reach the top tier.

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 clear invocation context ('Pass only the fields you want to change') and a concrete prerequisite ('Caller must own the goal or have the org.project.view.all permission'). It does not name alternatives or when-not-to-use cases, so it lacks the explicit routing of a 5.

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