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

Annotations already declare a safe read-only, non-destructive, closed-world operation, so the safety profile is covered. The description adds the handoff detail that the result is 'the two gapped rows' passed onward for grading, which is useful behavioral context, but it says nothing about alignment parameters, ambiguity handling, or failure modes.

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 tight sentence with the action and scope front-loaded and the downstream payoff trailing. No wasted clauses, though the phrasing is dense enough that the purpose clause takes a second read.

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, full annotation coverage, and 100% parameter documentation, the description only needs to frame what the tool is and what it produces. It does both, though it leaves the relationship to the many alignment/grading siblings for the agent to infer.

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 100%, so the read/reference/_subject/_files semantics are already fully documented in the schema, including the default-reference behavior. The description's mention of aligning 'against a reference' restates rather than extends that, so the 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 pairs a specific verb ('Pairwise-align') with a precise resource and scope ('ONE sequencing read against a reference'), which is enough to separate it from multi-sequence siblings like align_sequences or compare_reads_to_reference. It stops short of naming any sibling explicitly, so differentiation is inferred from the 'ONE read' scoping rather than stated.

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?

'so the read can be graded' hints at the downstream purpose (evaluating a read against its reference), which implies a usage context. However, the description never states when to pick this over align_sequences, verify_read, compare_reads_to_reference, or map_reads, and gives no prerequisites or exclusions.

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