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

Annotations already declare readOnly, idempotent, and non-destructive. The description adds behavioral traits such as 'cryptographic' and 'fixed-length digest,' and explains algorithm support including the default (SHA-256) and a recommendation for password hashing. This enriches the agent's understanding of output characteristics without contradicting 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 two crisp sentences: the first states the core function, the second packs use cases and algorithm list. No filler words.

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 tool with two parameters and an output schema, the description covers purpose, usage contexts, algorithm choices, and output nature (fixed-length digest). Combined with annotations and schema, the agent has everything needed to select and invoke 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?

The schema describes both parameters with 100% coverage, so the description doesn't need to repeat them. It does provide a small addition by recommending 'prefer SHA-256+' for password hashing, which helps with algorithm selection, but otherwise adds little beyond the 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?

The description uses the specific verb 'Compute' and resource 'cryptographic hash of a text string,' clearly distinguishing it from siblings like base64_encode (encoding) and generate_hmac (keyed hash). It also lists concrete use cases (data integrity, content fingerprints, password hashing), making the tool's purpose unmistakable.

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 states when to use the tool: 'Use when you need to verify data integrity, generate content fingerprints, hash passwords (prefer SHA-256+), or produce a fixed-length digest of any input.' This provides clear usage context, though it does not explicitly mention alternative tools like generate_hmac for keyed hashes, so it lacks explicit exclusions.

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