s3_head_bucket

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable behavioral context: it operates on the S3-compatible endpoint, checks both existence and reachability, and depends on current credentials. This goes beyond what the annotations convey, though it could mention explicit error/status outcomes.

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 tight sentences with no filler. The primary purpose is first, followed by a precise usage directive. Every phrase earns its place and nothing needs to be trimmed.

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 simple one-parameter, read-only tool with full annotations and complete schema coverage, this description supplies all necessary context: what it checks, what credentials it uses, and when to prefer it over a sibling. No missing information blocks an agent from selecting or invoking it correctly.

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% and the only parameter, 'bucket', is already described as 'The bucket name to check.' The description reinforces this by referencing the bucket but does not add new semantic details such as name format or restrictions. Baseline 3 is appropriate given full schema coverage.

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 ('Check whether') and resource ('B2 bucket') with the precise scope: exists and is reachable on the S3-compatible endpoint with current credentials. It also distinguishes itself from b2_list_buckets, removing any ambiguity with sibling tools.

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?

Explicitly gives the use case: 'Use this to validate S3-surface reachability' and directly names the alternative (b2_list_buckets) that does not cover S3 reachability. This tells an agent exactly when to choose this tool over a similar sibling.

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