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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that fragments are 'real' (sequence plus both overhangs), which implies a downstream record is produced, but it never says the emitted fragment is the one chosen by fragment_index or that nothing existing is modified.

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 verb and result front-loaded and no filler. Every clause carries information about what is produced.

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 four parameters, a nested _subject object and an output schema, the description is thin: it omits that fragment_index determines which fragment becomes the downstream record and says nothing about ordering beyond the schema. The output schema and fully documented parameters keep it from being inadequate.

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 the enzyme catalog resolution rule and the _subject source options, so the baseline is 3. The description only echoes 'the given enzymes' and adds no meaning about fragment_index or how enzymes interact with the active collection fallback.

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 (digest), the target resource (the subject) and a precise result (real fragments with sequence plus both overhangs). That distinguishes it from position-only siblings such as find_restriction_sites or enzyme_cut_counts, though no sibling is named explicitly.

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: use this when you need actual fragment records from a digest rather than cut sites or fragment sizes. There is no explicit when-to-use / when-not-to-use statement and no pointer to alternatives like size_fragments or ligate_fragments, leaving the agent to infer the boundary.

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