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

With no annotations, the description carries the burden and discloses meaningful behavior: it actually compresses the input to estimate gain, accepts base64 input, has a decoded byte limit, and requires HTTP body sizing for base64 overhead. It could say more about whether anything is persisted, but the key operational traits are covered.

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 front-loaded: it states purpose first, then input requirements, level behavior, returns, and size constraints. It is appropriately sized, though the single-paragraph format could be slightly easier to scan.

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?

There is no output schema and no annotations, but the description explains the returned metadata and per-level results, input constraints, and base64 sizing concerns. It is broadly complete for calling the tool correctly, with only minor unspecified edge cases such as error behavior.

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 0%, so the description must compensate. It explains fileBase64, the role of fileName and extensions in disambiguating Office formats, and the behavior of level when omitted versus set, adding substantial meaning 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?

The description states a specific verb and resource: detect a file and estimate compression gain by actually compressing it. It is clear enough to distinguish estimating from applying compression in general, but it does not explicitly contrast with the sibling compress_file tool.

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 useful operational guidance for the level parameter, including that omitting it estimates all presets and setting it targets one. However, it does not explicitly say when to use this tool instead of compress_file or list_compression_profiles, leaving sibling selection somewhat implied.

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