Burs-IA Utils

HMAC-SHA512

hmac-sha512

Read-onlyIdempotent

Calcula el HMAC (RFC 2104) con SHA512. Cuándo: hay que firmar un mensaje, o comprobar una firma, con un secreto compartido que viene en la llamada. No para: comprobar una firma HMAC en tiempo constante (hmac-verify). 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 SHA512 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: checking an HMAC signature in constant time (hmac-verify). 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

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the 'no side effects, no network' sentence is largely a restatement. What the description adds beyond the annotations is real, though: determinism and hard limits (64 KB JSON input, 1 s per call, 1 MB result).

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

Conciseness3/5

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

The labeled structure (When / Not for / Side effects / Deterministic / Limits) is well front-loaded with the scoping constraint first. However, the entire text is duplicated in Spanish and English, roughly doubling length with zero new information for an English-reading agent.

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?

With an output schema present the description needn't explain return values, and the annotations cover safety. What remains — when to use it, which sibling to prefer, determinism, and resource limits — is all present, so an agent has everything needed to call it correctly.

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

Parameters3/5

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

Schema description coverage is 100% with all five parameters documented and three enums constrained, so the schema already carries parameter meaning. The description only echoes the utf8/hex/base64 choices for data and key and says nothing about output_encoding, so it adds little beyond the baseline.

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 and resource (computes HMAC per RFC 2104 using SHA512) plus the supported data/key encodings, which pins it down against the many hash-* and hmac-* siblings. The named algorithm and the explicit contrast with hmac-verify let an agent pick it without opening any schema.

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:' and 'Not for:' clauses: sign or check a signature with a shared secret supplied in the call, but delegate constant-time verification to hmac-verify. That names the alternative and the condition that selects it, leaving nothing to inference.

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

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