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

The readOnlyHint already establishes that this is a safe read operation, and the description adds value by naming the computed breakdown and return fields, which matters because there is no output schema. It still does not discuss permissions, errors, or the expectedProjectId override behavior beyond what the schema says.

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?

The description is two sentences, front-loads the computation, then gives the visualization use case. There is no filler, and every clause contributes useful information.

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 read-only compute tool with no output schema, the description usefully names the return fields and the presentation context. It is nearly complete, but it could have clarified the relationship to compute_group_ownership or the cross-project targeting semantics.

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 description coverage is 100%, so the schema already explains both parameters, including the expectedProjectId targeting and access-refusal behavior. The description adds no parameter-specific meaning, so the baseline 3 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?

The description gives a specific verb and resource ('Computes ... direct ownership') and enumerates the outputs (totalShares, pricePerShare, per-holder shares/ownershipPct/valueAtPPS). It is clear what it does, though it does not explicitly contrast itself with the sibling compute_group_ownership.

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?

It says the result 'Serves the numeric recap or a table view visualization,' which implies a usage context. However, it does not state when to choose this over compute_group_ownership or when not to use it, leaving alternatives to inference.

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