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

Annotations already mark this as a non-read-only, non-idempotent write. The description adds genuinely useful behavioral details beyond that: the operation returns a generated supplier number, and the free tier is capped at 10 suppliers with removal freeing a slot. It does not cover duplicate handling or quota-exceeded errors, but it clearly adds context beyond the 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?

Two sentences, front-loaded with the core purpose and return value. The field enumeration is slightly redundant with the schema but serves as a compact summary; nothing is extraneous or rambling.

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 correctly fills the key gap by specifying the returned ID format. It also adds the free-tier limit and hints at the required fields (name, category). It does not describe error behavior for duplicates or quota overflow, but the rich input schema and annotations carry most of the load, making this nearly complete.

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%, so the input schema already documents all 10 parameters thoroughly. The description's list of fields (name, what they supply, contact, payment terms, lead time, notes) summarizes the schema but does not add new semantic meaning. Baseline 3 is appropriate.

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 clear action ('Add a supplier') and a specific resource ('the directory'), and distinguishes itself from siblings like supplier_update and supplier_remove by naming its unique return value, the SUP-YYYY-NNNN number. An agent can tell exactly what this tool does without opening the schema.

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 implies this tool is for creating a new supplier and adds useful quota context (free tier of 10, removal frees a slot). However, it never explicitly contrasts with sibling tools such as supplier_update for modifications or supplier_remove for deletions, so the agent must infer the boundary from tool names rather than guidance.

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