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

Beyond the annotations (destructiveHint=true, readOnlyHint=false), the description adds key behavioral details: 'goes live immediately' and the constraint that 'binary files must really be what their extension says.' It also mentions encoding requirements (utf8 vs base64). These enrich the behavioral contract beyond what annotations provide.

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 two sentences long and front-loads the core action. The second sentence is dense but efficient, covering encoding, alternative tool, and allowed types without unnecessary fluff. It earns its length.

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 file-publishing tool with no output schema, the description is thorough: it covers creation, replacement, deletion, encoding, size guidance, allowed file types, and binary integrity. It gives an agent everything needed to invoke correctly and know what to expect. No critical gaps remain.

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?

The description directly explains the encoding parameter ('Use utf8 for text and base64 for small binary files') and adds a validation constraint on binary files. While the schema already covers most parameters with descriptions (75% coverage), the description provides meaningful additional guidance on encoding and file-type integrity.

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 clearly states the verb and resource: 'Create, replace and delete files in one deploy that goes live immediately.' It distinguishes itself from siblings by mentioning the alternative start_upload for large files and specifying allowed file types. The purpose is unambiguous.

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 description gives explicit guidance for when to use start_upload instead ('For large or many files use start_upload instead'), which helps the agent route correctly. It also implies this tool is for small to medium file sets. However, it doesn't clarify the distinction between this tool's delete capability and the sibling delete_files tool, leaving some ambiguity.

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