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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: hits farther than the set's guaranteed correction radius are reported as NOT assigned, and this unassigned count is the signal of a failed run. It stops short of disclosing error handling or how to interpret borderline hits.

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, action-first ordering, no repetition of the title or annotations. The second sentence is dense and slightly convoluted (correction-radius concept plus the reporting critique), but every clause carries information an agent needs.

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?

An output schema exists, so return values need not be explained, and annotations cover the safety profile. The description supplies the key interpretive framing (unassigned reads are the diagnostic), but omits any pointer on metric selection or prerequisites, leaving a small gap for a 5-parameter tool with nested objects.

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 the schema already documents barcodes, reads, metric and _subject/_files. The description adds no parameter-level detail (e.g., that metric must match the error model the set was designed under, which the schema states and the prose omits). Baseline 3 is appropriate when the schema carries the parameter burden.

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 (assign) and resource (reads to their originating index), which is clearly distinct from alignment/trimming siblings like map_reads or trim_reads. It does not name an alternative tool or explicitly scope itself against them, but the action and the second half's focus on unassignable reads make the purpose unmistakable.

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 implied rather than stated: you call it when you have index reads and a barcode set and need per-index assignment plus a count of unreliable hits. There is no explicit when-to-use/when-not-to-use guidance and no named alternative (e.g., audit_barcodes, check_index_pool, map_reads) for related questions.

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