Decrypt a file (.s3enc)

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

Annotations already declare readOnlyHint/openWorldHint/idempotentHint, so the bar is lower, and the description still adds real substance: per-chunk verification, fail-closed semantics ('nothing is written' on wrong password, damage, truncation or reordering), and output-name sanitisation. It does not state whether an existing destination file is overwritten or what permissions are needed; the write-to-disk behavior also sits somewhat awkwardly next to readOnlyHint=true, though the description is explicit enough that no agent is misled about the write.

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 core behavior, failure conditions and output naming are front-loaded in one dense sentence, with the compatibility URL as a short trailing reference. No filler, though the URL line is only marginally useful for invocation.

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 no output schema, the description carries the burden for return semantics and does so for the failure case (errors reported, nothing written) and partially for success (file written under stored name, optional base64 via parameter). It never states what the success result contains (e.g., path returned) or overwrite behavior, a small but real gap for a file-producing tool.

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 all four parameters (file, output, password, returnBase64) are already documented, setting the baseline at 3. The description adds only indirect meaning — that a wrong password is detected and reported — and says nothing extra about output-path resolution or base64 return limits beyond the schema.

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 and resource ('Decrypt an .s3enc file'), names the exact producers of the input (the S3eidat website or crypto_file_encrypt), and names the output ('write the original file back under its stored (sanitised) name'). It is unmistakably distinct from crypto_text_decrypt and crypto_file_encrypt in the sibling list.

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?

It gives the precondition for use (the file must be .s3enc produced by the website or crypto_file_encrypt) and the counterpart that creates such files, which effectively routes the agent to crypto_file_encrypt for the inverse operation. It does not explicitly exclude or compare against crypto_text_decrypt or the other decrypt-adjacent tools, so it falls short of full 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.