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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine behavioural context beyond that: every line is tagged FACT, DERIVED or UNKNOWN, and the tool deliberately produces no ranking. That tells the agent how to interpret and present the result, which is real added value.

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?

A single sentence with an em-dash list, front-loaded with the core action and scope before the facet enumeration. Every clause carries information; the closing exclusion is compact. Slightly dense but no filler.

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?

No output schema exists, so the description must convey the return shape, and it does at a high level by naming the compared dimensions and the FACT/DERIVED/UNKNOWN labelling. For a one-parameter read-only tool this is close to sufficient; only the absence of any sibling routing leaves a small 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 description coverage is 100% and there is only one parameter, so the schema already carries the semantics. The description restates the 2-to-4 bound that minItems/maxItems enforce but adds no format or syntax detail beyond it. Baseline 3 applies.

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 (compare, side by side) and resource (Robinhood Chain projects) with an explicit cardinality (two to four). It enumerates the compared dimensions, so the agent knows the output facets. It stops short of explicitly contrasting itself with the near-neighbor project_diff or get_project_snapshot, so it is clear but not sibling-differentiated.

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?

The only usage signal is the negative constraint 'No winner and no recommendation', which tells the agent what not to expect rather than when to pick this tool over project_diff or a sequence of get_project_snapshot calls. No prerequisites, no when-to-use framing.

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