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

Annotations already establish that this is a safe, closed-world read, so the description's job is to add operational context — and it does, disclosing the row-per-probe-set shape and that each row carries the producer's call, its score, and the two thresholds it was graded against. It does not cover the file-resolution refusal behavior (unset file, multiple files), though that is documented in the schema instead.

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 sentence, front-loaded with the verb and resource, with no filler. It is dense — "the two thresholds that call was graded against" packs in output semantics — but every clause carries 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?

With an output schema present and annotations covering the safety profile, the description need not explain return values, and it is complete on what it does cover. The remaining gap is selection context: in a family of copy_number_read, copy_number_regions, copy_number_compare and similar tools, the description gives no routing signal to confirm this is the right one.

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 both the file and detected_only parameters are already well documented, including the default and the refusal-on-ambiguity behavior. The description adds nothing parameter-specific beyond the general framing of what a call row contains, which is the correct baseline for a fully described 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?

The description gives a specific verb ("Read") and a precisely bounded resource: the Affymetrix array result's own producer-supplied somatic calls, with the row granularity (one per mutation probe set) spelled out. This implicitly separates it from the derived-analysis siblings like copy_number_segment or copy_number_loh, but it never names those siblings, so an agent must infer the distinction.

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?

Usage is only implied: the phrase "the result's own somatic-mutation calls" suggests this is the tool for reading producer calls rather than recomputing them, and the detected_only semantics hint at the wild-type-versus-absent distinction. There is no explicit when-to-use statement, no when-not-to-use, and no named alternative among the eight copy_number_* siblings.

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