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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral facts: an access right is required on EVERY listed robot, and a single missing right produces a refusal naming that robot with nothing compared — an all-or-nothing failure mode an agent must know before calling.

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?

Two sentences, zero waste. The scope and comparison dimensions come first, and the precondition/failure clause follows — exactly the right ordering for a pre-call decision.

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 comparison tool with a one-parameter schema and no output schema, the description covers what is compared and the blocking failure mode well. The only real gap is the ID list encoding, which matters because it is the sole required input.

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 0% and the single parameter is an undescribed string, so the description must compensate. It does supply the critical 2-to-5 cardinality bound, but never explains how multiple robot IDs are encoded in that string (comma-separated, repeated, etc.), leaving the main practical ambiguity unresolved.

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), resource (robots), and the exact dimensions compared (mechanical BOM, specifications, risk, geographic exposure). The 'mechanical' qualifier cleanly separates it from hardware_compare_robots and software_compare_robots in the sibling set.

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 2-to-5 cardinality constraint is stated, which shapes how the tool should be called, and the mechanical framing implies the domain relative to its hardware/software siblings. However, it never explicitly says when to choose this over hardware_compare_robots or software_compare_robots, nor does it name any alternative.

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