execute_capability

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

No annotations provided, so description carries full burden. Discloses critical security behavior ('NEVER stored by Rhumb — used for this single request only'), auto-selection logic ('auto-selects the best healthy provider'), and fallback requirements ('Required to enable automatic fallback'). Missing operational details like rate limits or timeout behavior.

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 dense sentences efficiently pack mode definitions and sibling references. Parenthetical explanations are effective, though the first sentence is information-dense. No wasted words; every clause adds specific parameter or mode requirements.

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 complex 9-parameter execution tool with credential management, covers execution modes, prerequisites, security implications, and provider selection. Adequate without output schema, though brief mention of error handling or response format would strengthen completeness further.

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 has 100% coverage (baseline 3). Description adds valuable cross-parameter logic: explains how credential_mode affects method/path requirement cardinality, specifies agent_token provenance (credential_ceremony), and adds security context not present in schema.

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?

Clear specific verb ('Execute') + resource ('capability'), domain context ('through Rhumb'), and distinguishes from siblings by referencing resolve_capability (for discovery) and check_credentials (for validation) as prerequisite steps rather than execution.

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?

Excellent explicit guidance: defines three credential modes with specific requirements (byo requires method+path; rhumb_managed is zero-config; agent_vault requires agent_token from credential_ceremony). Directly references sibling tools for prerequisite steps and clearly maps parameter dependencies to modes.

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