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

The description discloses key behaviors: it does not unpack anything, returns text inline, and refuses binary entries by name rather than printing noise. Since annotations provide no positive safety profile (readOnlyHint false, destructiveHint false, etc.), this behavioral detail carries value beyond the schema. It does not mention side effects (likely none) or permissions, but the provided traits are helpful and non-contradictory.

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 compact: two sentences that immediately state the invocation context and a key behavioral constraint. It is front-loaded with the core action ('read one text entry... without unpacking'), followed by a valuable edge-case note. No redundant or filler phrases.

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 small, focused read tool with three parameters and no output schema, the description covers the core capability, the no-unpacking behavior, and the binary-entry refusal. It does not mention return format details (though 'text comes back inline' gives a hint) or prerequisites like using zip_list to find entry names, but the schema's reference to zip_list partially covers that. The description is adequate for simple usage without major gaps.

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 the schema fully documents all three parameters. The description adds minimal semantic value beyond the schema—'give the entry name and the text comes back inline' simply reinforces the entry parameter's effect but does not specify formats, defaults, or edge cases beyond what the schema already states. Baseline 3 is appropriate.

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: 'read one text entry out of an archive without unpacking anything.' It clearly differentiates from zip_extract by emphasizing no extraction occurs, and the title 'Read one entry as text' reinforces the scope. An agent can distinguish this from siblings like zip_list (listing) and zip_extract (extracting) without opening schemas.

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?

The opening phrase 'Call this tool to...' provides clear context for when to use it: when a single text entry is needed inline without extraction. However, it does not explicitly name alternatives or state when not to use it (e.g., 'use zip_extract for binary files'), though the binary-refusal note implies such an exclusion. This is a clear context but lacks explicit sibling routing.

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