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

With no annotations provided, the description carries the full behavioral burden. It does disclose a meaningful behavioral trait: the tool 'computes' deltas and stability spread rather than mutating data, and it establishes a 'primary baseline disc' framing. It does not, however, say what happens with invalid/unknown disc IDs, how the baseline is chosen, or what the response structure will be.

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?

One tightly packed sentence states the action, the valid count range, the comparison mode, and the computed metrics. Every phrase earns its place, and there is no filler or repetition of the schema.

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 single-parameter tool with full schema coverage and no nested objects, the description is nearly complete: it states the operation, the input cardinality, and the key computed outputs. Since there is no output schema, a slightly more explicit statement of the return shape would close the last gap, but the mention of deltas and stability spread gives adequate context.

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?

The schema already fully documents disc_ids as an array of 2 to 4 IDs or slugs, so the baseline is 3. The description adds genuine operational meaning by introducing the 'primary baseline disc' concept, which implies ordering significance in disc_ids. This is meaningful context beyond the schema's generic array description.

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 uses a specific verb ('Compare') and resource ('discs'), and clearly distinguishes this tool from siblings by adding the scope '2 to 4 discs side-by-side' and the unique output concept of 'flight rating deltas and stability spread'. It is immediately obvious this is not get_disc, search_discs, or find_similar_discs.

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 description makes the core use case clear: compare a set of 2–4 discs relative to a primary baseline. However, it does not explicitly state when to prefer this over find_similar_discs or search_discs, and there are no exclusion conditions or alternative routing hints. Usage context is implied rather than prescribed.

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