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

Annotations already declare non-readOnly, idempotent, non-destructive, closed-world. The description adds genuinely new behavioral context: the call returns character/line counts and detected language but 'never its text', which tells the agent what it can and cannot rely on afterwards. That is real value beyond the annotation set, though it says nothing about failure modes or what happens if the PUT never occurred.

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?

Two sentences, both front-loaded with the action and then the payoff. No restatement of the name or title and no filler.

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?

An output schema exists, so return values need not be spelled out, yet the description still usefully characterizes them and explains the handoff to a source_script node. The only meaningful omission is that the upstream prerequisite (upload_script_file / the PUT step) is implied rather than named.

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 both parameters (upload_id, workflow_id) are already fully documented in the schema, including the workflow_id omit-to-keep-in-workspace semantics. The description only reinforces upload_id's provenance, so the baseline 3 applies.

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 ('Register a file whose bytes you already PUT to an upload_url') and implicitly scopes itself against the sibling upload_script_file by making clear this is the completion half of a two-phase upload. An agent can distinguish it from upload_script_file without opening either schema.

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?

Gives clear sequencing context (bytes already PUT to an upload_url) and prescribes the downstream usage: 'Pass the upload_id to a source_script node as input_type="file", upload_ids=[upload_id]'. It stops short of explicitly naming upload_script_file as the required predecessor, leaving that inference to the schema's upload_id description.

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