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

Annotations already declare readOnlyHint=true and idempotentHint=true, but the description goes far beyond that. It explains the non-templated 5' tail behavior, clarifies that primers prime on the 3' end, defines start/end as template-derived span and length as including tails, and mentions the 'features' field and per-end annealedLength/tailLength in the output. This rich behavioral context, including edge cases like circular templates and search-window semantics for maxProductLength, adds substantial transparency.

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?

The description is dense but every sentence earns its place. The core purpose leads, followed by the tail mechanism, then parameter semantics. There is no fluff or repetition, and technical details like the start/end vs length distinction are packed efficiently. It is appropriately long for the complexity but remains tightly structured.

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?

Given 6 parameters, no output schema, and a complex tool, the description covers everything an agent needs to call it correctly: primer orientation, tail handling, circular behavior, mismatch tolerance, and even the semantics of maxProductLength plus the response fields (features, annealedLength, tailLength, suppressedByLength). It is fully self-contained despite the absence of an output schema.

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?

The schema already provides descriptions for all 6 parameters (100% coverage), but the description adds crucial nuance: it clarifies that reversePrimer is optional and order-independent, explains the tail interpretation for forwardPrimer, and reinterprets maxProductLength as a 'SEARCH WINDOW' that discards products via suppressedByLength. This goes well beyond the schema to resolve ambiguity and correct potential misinterpretations.

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 immediately states the specific verb and resource: 'Predict PCR products for a template and a pair of primers'. It further distinguishes itself by listing key capabilities (IUPAC-aware, allows mismatches, handles circular templates) that separate it from primer design tools like primer_design. This makes its purpose clear and non-confusable with siblings.

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 explicit. The description says what it does but never directly states when to use it over alternatives or when not to use it. The only hint is the mention of 'whole-plasmid inverse PCR' in the maxProductLength parameter, which implicitly ties it to cloning workflows but does not contrast with other sibling tools. There is no explicit when/when-not guidance.

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