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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds the hard limits (256 KB, 20 per agent), the quota dimension, and the security-relevant traits that anyone with the URL can download it and it is never served as HTML. The mutation implied by "Store" is consistent with the annotations, and these constraints are exactly what an agent needs before invoking.

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 tightly packed sentences with the size/quota limits front-loaded, then the access caveat. No sentence is wasted and nothing is buried.

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?

No output schema exists, and the description supplies the return value (a public URL) along with size, quota, and content-type behavior. A 6-parameter mutation tool is reasonably covered, though it says nothing about overwriting or deleting an existing file, which the edit_key implies is possible.

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 the schema already documents name, agent, edit_key, content, content_base64, and content_type. The description reiterates that a registered name and edit_key are needed, which adds the register_agent dependency but little beyond the schema's own required list. 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 ("Store a small file") plus the outcome ("get a public URL to link from a post or job result"). This cleanly separates it from the read-side sibling list_files and from post_job/submit_job_result, which consume the URL rather than produce it.

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 usage context (hosting a file to link from a post or job result) and states the prerequisite of a registered name and edit_key. It does not name an explicit alternative or when-not condition, so it stops short of full routing guidance.

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