Stack local images

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

Annotations cover the safety profile (not read-only, not destructive), and the description adds real operational context beyond them: it writes and verifies an output file, needs a local browser, and refuses non-local paths. It does not say what happens if output_path already exists (overwrite vs. fail), which is the main remaining behavioral gap.

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?

Three tightly packed sentences with the capability front-loaded and limitations trailing. The clipped enumeration style ('No alignment, rescaling, RAW decoding or focus stacking') is efficient rather than wasteful.

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?

For a 7-parameter write tool with no output schema, the description covers inputs, methods, constraints and the fact an output file is written and verified. It falls short on the semantics of gain/kappa/quality and on overwrite/conflict behavior, which an agent needs before committing a write.

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 only 14%, so the description must carry weight. It does map the method names (average, median, sigma-clipped, brightest, darkest, additive) onto the enum values, but gain, kappa and quality are never explained, leaving three of seven parameters undocumented anywhere.

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 (combine) and resource (2-8 equal-size opaque still images) with the full method list enumerated. It also carves out scope boundaries explicitly ('No alignment, rescaling, RAW decoding or focus stacking'), which no sibling tool covers.

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?

Clear preconditions are given: images must already line up, must be equal-size, opaque and still, and a local browser is required. The negation list implicitly routes alignment/rescaling/RAW/focus-stacking work elsewhere, though no sibling is named directly.

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