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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral note — no object content is transferred — but says nothing about permissions, consistency, or behavior for missing keys, so with annotations doing the heavy lifting this is only modest added value.

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?

A single front-loaded sentence with zero filler; the returned fields and the key constraint ('without reading it') are both delivered immediately.

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?

With no output schema, the description does enumerate the fields returned (size, content type, user metadata), which is what an agent needs to judge usefulness, and annotations cover the safety profile. Minor gaps remain around error cases and whether user metadata may be null when absent.

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% with all three required params (key, bucket, connectionId) documented, including the pointer to list_connections for connectionId. The description adds no parameter-level meaning beyond the schema, 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 the exact resource returned (size, content type, user metadata for one object) and scopes it to a single object. It implicitly separates itself from read_object by saying 'without reading it', but does not name the sibling explicitly, so it falls just short of a 5.

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 phrase 'without reading it' communicates the condition that selects this tool over read_object — use it when only metadata is needed and the bytes/egress should be avoided. It gives clear context but never names alternatives or exclusions outright.

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