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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true; the description adds real substance on top by disclosing the slug lock, the all-or-nothing semantics ('writes nothing' on stale version), and three named error outcomes with their triggers. It stays consistent with the annotations — committing a version is both destructive and idempotent per the hints. It doesn't say whether the session is consumed after success.

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?

Front-loaded action clause followed by a compact inputs list and a terse error table; nearly every clause carries information. The 'Inputs:' enumeration is the one segment that mostly duplicates the schema.

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 destructive, no-output-schema commit tool, the description covers the locking model, atomicity, and the three failure outcomes an agent must branch on. The remaining gap is what a successful response returns and whether the upload session survives it, which matters for retry logic.

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 coverage is 100%, so all five parameters are already documented in the input schema, including the redaction and header-override rules. The description's 'Inputs:' list largely restates that, adding only the expected_version-to-version_conflict mapping, which the schema also states. Baseline 3 fits.

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?

Opens with a concrete three-step verb chain — checks hashes, screens bytes, commits one version under the slug lock — so the agent knows this is the terminal step of a write flow, not a read or a plan. It never names plan_upload, so the boundary with the closest sibling is only inferable from the word 'commits'.

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 'upl_...' session prefix and the commit framing imply this runs after a planned upload, and the three named failure modes sketch the preconditions. But there is no explicit 'call this after plan_upload / after uploading parts' instruction and no statement of when not to use it or what to do instead on failure.

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