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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds genuine behavioral content by disclosing the exact screening criteria (GC gate, intra-spacer hairpins, backbone hairpins) and that the behavior mirrors CHOPCHOP. It stops short of stating pass/fail thresholds or how rejected spacers are reported, but the output schema covers the return shape.

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 the core action front-loaded and the three checks listed in order of operation. No filler, no restatement of the tool name.

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 annotations, a full output schema, and complete parameter descriptions, the description only needs to convey purpose and algorithm, which it does. The only notable omission is the GC threshold or rejection criteria, but that is arguably output-schema territory.

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%, including detailed notes on gg, pre_g, backbone, and spacers, so the schema carries the parameter burden. The description adds no parameter-specific meaning beyond what the schema already states; 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?

The description names a specific verb (screen) and resource (guide spacers) and enumerates the three checks performed — GC gate, self-complementary hairpins within the spacer, and hairpins against the sgRNA backbone. That is enough to distinguish it from siblings like fold_guide or search_off_targets, though it never explicitly names an alternative.

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 phrase 'before it accepts them' implies this is a pre-acceptance QC step, but there is no explicit when-to-use guidance, no exclusions, and no pointer to an alternative tool for off-target or efficacy scoring. Usage must be inferred.

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