Burs-IA Utils

HMAC-SHA3-256

hmac-sha3-256

Read-onlyIdempotent

Calcula el HMAC (RFC 2104) con SHA3-256. Cuándo: hay que firmar un mensaje, o comprobar una firma, con un secreto compartido que viene en la llamada. No para: calcular el resumen SHA3-256 (hash-sha3-256). Efectos secundarios: ninguno (solo lectura, sin red, sin estado guardado). Determinista: la misma entrada da la misma salida. Límites: entrada JSON de hasta 64 KB, 1 s por llamada, resultado de hasta 1 MB.

EN: Computes the HMAC (RFC 2104) using SHA3-256 over text, hex or base64 data with a text, hex or base64 key. When: a message has to be signed, or a signature checked, with a shared secret supplied in the call. Not for: computing the SHA3-256 digest (hash-sha3-256). Side effects: none (read-only, no network access, no stored state). Deterministic: the same input gives the same output. Limits: JSON input up to 64 KB, 1 s per call, result up to 1 MB.

Input Schema

Name	Required	Description	Default
`key`	Yes	Secret key (string; required; up to 4096 chars).
`data`	Yes	Input data (string; required).
`key_encoding`	No	Encoding of `key` (optional; one of: utf8, hex, base64; default "utf8").	utf8
`input_encoding`	No	How `data` is encoded (optional; one of: utf8, hex, base64; default "utf8").	utf8
`output_encoding`	No	Output encoding of the digest (optional; one of: hex, base64, base64url; default "hex").	hex

Output Schema

Name	Required	Description	Default
`mac`	No
`encoding`	No
`algorithm`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedNov 2, 2026
- addedInput schema / properties / data / examples
```
Added value: +[
+  "The quick brown fox jumps over the lazy dog"
+]
```
- addedInput schema / properties / key / examples
```
Added value: +[
+  "key"
+]
```
First observedNov 1, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description adds substantive context beyond them: 'no network access, no stored state', determinism, and concrete limits (64 KB JSON, 1 s per call, 1 MB result). These limits are operationally useful and not present in annotations or schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Each sentence earns its place (purpose, when, not-for, side effects, determinism, limits) and the key facts are front-loaded. The cost is full ES/EN duplication, which roughly doubles length for the same content, keeping it from a 5.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given a rich schema, full annotations, and an output schema (so return format need not be explained), the description covers everything an agent needs: purpose, boundaries, side effects, determinism, and hard limits. Nothing material is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline would be 3, but the description adds genuine semantics by summarizing the encoding dimensions ('text, hex or base64 data with a text, hex or base64 key'), clarifying that both data and key are encoding-configurable. It does not explain output_encoding, but the schema already enumerates it.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource with algorithm and standard: 'Computes the HMAC (RFC 2104) using SHA3-256 over text, hex or base64 data with a text, hex or base64 key.' It explicitly names the sibling it is not (hash-sha3-256), so an agent can separate signing from plain hashing without inspecting schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Uses explicit 'When:' (sign or verify with a caller-supplied shared secret) and 'Not for:' (SHA3-256 digest, hash-sha3-256) framing, giving both inclusion and exclusion conditions with the named alternative. This is the strongest form of routing guidance.

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

All Burs-IA Utils tools Inspect

Try in Browser

Shareable, User-Owned Context BackendPeople, applications, and agents read, write, and coordinate together in one context lake. Reach it over MCP, a CLI, a Python SDK, or REST.fulcradynamics.comAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?