Whoami

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

With no annotations provided, the description fully carries the behavioral burden and does so thoroughly. It discloses the request cost, that no roster data is fetched, exactly what fields are returned, and the failure mode with an explanatory message when cookies expire or the league/team cannot be resolved. This is model behavior for a zero-annotation tool.

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 three short, information-dense sentences with no filler. It front-loads the core purpose and 'Call this first' instruction, then supplies cost, return details, and failure behavior. Every sentence earns its place.

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 zero-parameter preflight tool with an output schema present, the description is complete: it covers when to call it, what it returns, cost characteristics, failure modes, and error messaging. There is no significant information an agent needs that is missing. The output schema handles return-value detail, so the description's summary of return fields is sufficient.

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 tool has zero parameters and the schema trivially covers this with an empty properties object. Per the baseline for zero-parameter tools, the description need not add parameter semantics. It adds value by describing what is returned rather than parameters, which is appropriate here.

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 a specific action: 'Verify ESPN credentials and league configuration', and the phrase 'Call this first' immediately positions it as a preflight/bootstrap check. It distinguishes itself from sibling data-fetching tools by noting it returns the league and team identifiers, not league settings, matchup, or free-agent data. This is enough for an agent to know what the tool is for and how it differs from siblings.

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 explicitly says 'Call this first' and supports that with cost and scope information: 'Cheap (one small request, no roster data)'. This gives concrete guidance on when to invoke it before more expensive or data-heavy sibling calls. It also indicates when not to expect detailed data, effectively distinguishing it from retrieval tools.

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