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

Annotations already state readOnlyHint=true, but the description goes far beyond that by specifying the exact return shape ({ valid, available }), the meanings of each value (valid=false for malformed, available=false for taken, available=null for inconclusive), and the note that create_draft still enforces uniqueness even when inconclusive. This discloses edge-case behavior that annotations cannot convey. There is no contradiction with annotations.

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 information-dense but well-structured: it leads with the core action and purpose, then explains the return contract, then the validation rules, then the preferred alternative. Every sentence earns its place; there is zero filler or repetition. The critical guidance is front-loaded, and the alternative is stated at the end without weakening the primary message.

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 single-parameter, read-only validation tool with a fully documented schema and an output schema, the description is complete. It covers the tool's purpose, the expected return values and their edge cases, and explicitly routes the user to the preferred alternative. There is nothing an agent needs to know to call this correctly that is missing.

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 schema describes slug as a string with format 'kebab-case, 3–60', but the description expands on this with concrete validation rules: 'no leading/trailing hyphen' and explains how the slug's validity maps to the return values. This adds practical meaning beyond the schema's type constraints, showing the agent exactly what constitutes a valid input.

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 uses a specific verb ('Check'), a clear resource ('agent slug'), and the exact criteria ('well-formed AND available'). It explicitly distinguishes itself from siblings by stating it runs 'before findagent_create_draft' and naming the recommended alternative findagent_submission_wizard. An agent can immediately understand the tool's function without any ambiguity.

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 provides explicit usage context: 'before findagent_create_draft' sets the timing, and 'Prefer findagent_submission_wizard' directly names the alternative and indicates it should be chosen over this tool in normal flows. This is a clear when-to-use and when-not-to-use directive, with a specific alternative named.

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