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mcp-lrclib

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LRCLIB is a free, open database of song lyrics, built by the people who use it and offered to anyone without a key or an account. It holds two forms of the words: the plain text of a song, and the LRC form, where every line carries the moment it is sung, which is what a karaoke display or a lyrics panel follows along with. A track is filed there by its title, its artist, its album and its duration, so the several releases of one song sit side by side.

This server connects a chat client to that database. You can search for a track by title, artist or album, read the plain words of a song, read its time-synced lines with their timestamps, and check the metadata of one release before reading it. It needs no API key and no account.

Version française


Install

One-click install

Install in Cursor Install in VS Code

Claude Code

claude mcp add lrclib -- npx -y mcp-lrclib

Claude Desktop, Cursor, and any client using the standard config format

{
  "mcpServers": {
    "lrclib": {
      "command": "npx",
      "args": ["-y", "mcp-lrclib"]
    }
  }
}

Node 24 or later is required, and no environment variable has to be set.

With Docker

{
  "mcpServers": {
    "lrclib": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/smeet666/mcp-lrclib:2.0.1"]
    }
  }
}

-i keeps stdin open, which is where the protocol travels, and -t is left out because a TTY rewrites the stream. The container needs outbound HTTPS to lrclib.net, and nothing else: no volume, no port, no credential.

Bundle, without npm

Download mcp-lrclib-2.0.1.mcpb from the latest release and open it. A client that supports MCP bundles installs it on its own, with no npm and no configuration file to edit. The bundle carries its dependencies, so nothing is fetched at install time.

Related MCP server: LyricsGenius MCP Server

What you can ask

  • "Find me the lyrics of Le Sud by Nino Ferrer."

  • "Give me the timed lyrics of Bohemian Rhapsody so I can follow along."

  • "Which version of Hallelujah is on LRCLIB, and how long is each one?"

  • "Read me the second half of those lyrics."

  • "Does track 3396226 have synced lyrics?"

The ordinary path runs from a search to a reading: search_tracks names an id, and get_lyrics takes that id.

Tools

Tool

What it does

search_tracks

Finds tracks by title, artist or album, with their metadata.

get_lyrics

Reads the words of one track, plain or with their timestamps.

get_track

Reads the metadata of one track by its id, without the words.

LRCLIB files a track by its metadata, so a search reaches a song through its title, its artist or its album. A word remembered from inside a song finds nothing there.

search_tracks

Finds the tracks whose metadata matches, in one free-text search or in fields of their own. Several releases of one song come back side by side, and their album and duration tell them apart.

Argument

Type

Required

What it does

query

string, 1 to 200 characters

no

Free-text search, as in nino ferrer le sud.

track_name

string, up to 200 characters

no

Song title, for a search by field.

artist_name

string, up to 200 characters

no

Artist name, for a search by field.

album_name

string, up to 200 characters

no

Album name, to narrow a search by field.

limit

integer, 1 to 50, default 10

no

Rows to serve. LRCLIB answers up to 20 per search.

Pass query, or one of the three fields.

In return: rows carrying id, which get_lyrics and get_track take; track_name and artist_name; album_name and duration_seconds, which tell two releases of one song apart; instrumental; has_plain_lyrics and has_synced_lyrics, so timed lines can be checked for before they are asked for; and source_url. Alongside come result_count and total_available, the tracks LRCLIB served before limit was applied. album_name and duration_seconds are null on a track filed without them, and the rows carry no words at all: get_lyrics reads those.

get_lyrics

Reads the words of one track, either as plain text or as LRC lines carrying the moment each one is sung. Long lyrics are served a slice at a time, resuming at a line boundary.

Argument

Type

Required

What it does

id

integer, positive

no

The LRCLIB track id, as search_tracks returned it.

artist_name

string, up to 200 characters

no

Artist name, matched exactly. Needed when id is absent.

track_name

string, up to 200 characters

no

Song title, matched exactly. Needed when id is absent.

album_name

string, up to 200 characters

no

Album name, to pick between releases.

duration_seconds

number, positive

no

Track duration, to pick between versions of differing length.

format

plain, synced or both, default plain

no

Which form of the words to serve.

max_chars

integer, 200 to 20000, default 6000

no

Characters of text to serve in this call.

offset

integer, 0 or more, default 0

no

Character offset to resume from.

In return: status, which reads ok, instrumental for a track with no words to sing, or no_lyrics for one filed without them; track with its id, title, artist, album, duration and source_url; plain_lyrics; synced_lyrics as raw LRC text and synced_lines as a list of { time_seconds, text }, with synced_lines_truncated when the slice cut them. The reading is described by paginated_form, total_chars, returned_chars, offset, next_offset and truncated: pass next_offset back to read on, and null there means the end. attribution is the line to cite when the words are shown. A status of instrumental is a complete answer.

get_track

Reads the metadata of one track from its id, leaving the words aside. It confirms a release before the words are asked for, and it resolves an id carried over from earlier in a conversation.

Argument

Type

Required

What it does

id

integer, positive

yes

The LRCLIB track id, as search_tracks returned it.

In return: track, holding the fields a search row carries, and duration_formatted as m:ss, which is null when the track is filed without a duration. has_plain_lyrics and has_synced_lyrics say which forms get_lyrics can serve for it.

Configuration

Every variable is optional. Set them in the env block of your client config.

Variable

Default

What it does

LRCLIB_USER_AGENT

the project identity

Names your application to LRCLIB, with an address where a person can be reached.

LRCLIB_MIN_INTERVAL_MS

500

Gap between two requests, from 200 to 60000. A figure under the floor is refused and this one used.

LRCLIB_TIMEOUT_MS

15000

Deadline for one request, from 1000 to 120000.

LRCLIB_MAX_RETRIES

3

Attempts after a transient failure, from 0 to 10.

LRCLIB_CACHE_TTL_MS

900000

How long an answer stays in memory, from 0 to 86400000.

LRCLIB_CACHE_MAX_ENTRIES

200

Answers held in memory at once, from 0 to 10000.

LRCLIB_LOG_LEVEL

error

silent, error, info or debug, written to stderr.

A value outside its range falls back to the default, and the reason is written to stderr.

Errors

Every failure carries one of six codes, a message, and where it helps a hint naming the next move.

Code

What happened

What to do

not_found

LRCLIB answered, and it holds no such track.

Check the spelling with search_tracks.

invalid_input

The arguments were refused before any request went out.

Read the message, which names the argument.

rate_limited

LRCLIB asked this client to slow down.

Wait the number of seconds the hint names and call again with the same arguments. The track is still there.

upstream_error

LRCLIB answered in a shape this client cannot read.

Report it at the issue tracker.

network_error

The request did not complete.

Try again shortly.

timeout

The request passed its deadline.

Raise LRCLIB_TIMEOUT_MS, or ask for a smaller max_chars.

As a library

The layer reading LRCLIB is published on its own, with its pacing, its cache and its errors, and with no protocol attached.

import { LrclibClient } from "mcp-lrclib/client";

const client = new LrclibClient();
const { data, cached } = await client.getById(3396226);
console.log(data.track_name, data.synced_lyrics !== null, cached);

search, get and getById each answer { data, cached }, and throw an error carrying one of the six codes. The floor between two requests holds here as well.

Pacing and attribution

Requests go out one at a time with a minimum gap between them, and that floor holds however the server is configured. The User-Agent always ends with the project identity and an address where a person can be reached. LRCLIB is a free service and publishes its API for machines to read, and this server reads it on demand, one call at a time, in answer to something you asked for.

Every result carries the artist, the title and the address of its LRCLIB page, and get_lyrics carries attribution, the three of them written as one line.

Song lyrics are the work of their authors and publishers. This project claims no rights over them, ships no database of them, writes nothing to disk, and contributes nothing back to LRCLIB. This MCP server is an unofficial project, with no affiliation to LRCLIB.

Privacy

This server collects nothing about you and sends nothing to its author. It runs on your machine, contacts lrclib.net and nothing else, holds its answers in memory while it runs, and writes nothing to disk. PRIVACY.md states what a request carries and which settings change any of it.

Development

npm install
npm run build:fixtures
npm test
npm run check

Tests run against generated fixtures and make no network request. The live suite, npm run test:live, makes one request per route and runs nightly against the service itself.

Contributing

Bugs, questions and ideas belong in the issue tracker. Pull requests are welcome; opening an issue first helps agree on the shape of the change. See CONTRIBUTING.md.

License

MIT, see LICENSE. The lyrics belong to their authors and publishers, and the database to LRCLIB and its contributors.


mcp-lrclib (français)

English version

LRCLIB est une base de paroles de chansons libre et ouverte, alimentée par ceux qui s'en servent et offerte à tous sans clé ni compte. Elle contient deux formes des paroles : le texte simple d'une chanson, et la forme LRC, où chaque ligne porte le moment où elle est chantée, ce que suit un affichage karaoké ou un panneau de paroles. Un titre y est classé par son nom, son artiste, son album et sa durée, si bien que les différentes parutions d'une même chanson y voisinent.

Ce serveur relie un client de conversation à cette base. On peut y chercher un titre par son nom, son artiste ou son album, lire les paroles simples d'une chanson, lire ses lignes horodatées avec leurs marques de temps, et vérifier la fiche d'une parution avant de la lire. Aucune clé d'API, aucun compte.

Installation

Installation en un clic

Install in Cursor Install in VS Code

Claude Code

claude mcp add lrclib -- npx -y mcp-lrclib

Claude Desktop, Cursor, et tout client au format de configuration standard

{
  "mcpServers": {
    "lrclib": {
      "command": "npx",
      "args": ["-y", "mcp-lrclib"]
    }
  }
}

Node 24 ou plus récent est nécessaire, et aucune variable d'environnement n'est à renseigner.

Avec Docker

{
  "mcpServers": {
    "lrclib": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/smeet666/mcp-lrclib:2.0.1"]
    }
  }
}

-i garde l'entrée standard ouverte, qui est le canal du protocole, et -t est omis parce qu'un TTY réécrit le flux. Le conteneur a besoin d'un accès HTTPS sortant vers lrclib.net, et de rien d'autre : aucun volume, aucun port, aucun identifiant.

Bundle, sans npm

Téléchargez mcp-lrclib-2.0.1.mcpb depuis la dernière publication et ouvrez-le. Un client qui gère les bundles MCP l'installe seul, sans npm et sans fichier de configuration à modifier. Le bundle emporte ses dépendances, donc rien n'est téléchargé à l'installation.

Ce qu'on peut demander

  • « Trouve-moi les paroles du Sud de Nino Ferrer. »

  • « Donne-moi les paroles horodatées de Bohemian Rhapsody pour que je suive. »

  • « Quelles versions de Hallelujah y a-t-il sur LRCLIB, et quelle est leur durée ? »

  • « Lis-moi la seconde moitié de ces paroles. »

  • « Est-ce que le titre 3396226 a des paroles synchronisées ? »

Le chemin ordinaire va d'une recherche à une lecture : search_tracks nomme un id, et get_lyrics reprend cet identifiant.

Les outils

Outil

Ce qu'il fait

search_tracks

Trouve des titres par nom, artiste ou album, avec leurs fiches.

get_lyrics

Lit les paroles d'un titre, simples ou horodatées.

get_track

Lit la fiche d'un titre par son identifiant, sans les paroles.

LRCLIB classe un titre par sa fiche, donc une recherche atteint une chanson par son nom, son artiste ou son album. Un mot retenu de l'intérieur d'une chanson n'y trouve rien.

search_tracks

Trouve les titres dont la fiche correspond, en une recherche libre ou par champs. Plusieurs parutions d'une même chanson reviennent côte à côte, et leur album et leur durée les distinguent.

Argument

Type

Requis

Ce qu'il fait

query

chaîne, 1 à 200 caractères

non

Recherche libre, par exemple nino ferrer le sud.

track_name

chaîne, jusqu'à 200 caractères

non

Nom de la chanson, pour une recherche par champs.

artist_name

chaîne, jusqu'à 200 caractères

non

Nom de l'artiste, pour une recherche par champs.

album_name

chaîne, jusqu'à 200 caractères

non

Nom de l'album, pour resserrer une recherche par champs.

limit

entier, 1 à 50, défaut 10

non

Lignes à servir. LRCLIB en rend jusqu'à 20 par recherche.

Passez query, ou l'un des trois champs.

En retour : des lignes portant id, que get_lyrics et get_track reprennent ; track_name et artist_name ; album_name et duration_seconds, qui distinguent deux parutions d'une même chanson ; instrumental ; has_plain_lyrics et has_synced_lyrics, qui permettent de vérifier l'existence des lignes horodatées avant de les demander ; et source_url. Viennent aussi result_count et total_available, les titres que LRCLIB a servis avant l'application de limit. album_name et duration_seconds valent null sur un titre classé sans eux, et les lignes ne portent aucune parole : get_lyrics les lit.

get_lyrics

Lit les paroles d'un titre, en texte simple ou en lignes LRC portant le moment où chacune est chantée. Des paroles longues sont servies par tranches, coupées sur une fin de ligne.

Argument

Type

Requis

Ce qu'il fait

id

entier, positif

non

L'identifiant LRCLIB rendu par search_tracks.

artist_name

chaîne, jusqu'à 200 caractères

non

Nom de l'artiste, correspondance exacte. Nécessaire sans id.

track_name

chaîne, jusqu'à 200 caractères

non

Nom de la chanson, correspondance exacte. Nécessaire sans id.

album_name

chaîne, jusqu'à 200 caractères

non

Nom de l'album, pour choisir entre des parutions.

duration_seconds

nombre, positif

non

Durée du titre, pour choisir entre des versions de longueurs différentes.

format

plain, synced ou both, défaut plain

non

La forme des paroles à servir.

max_chars

entier, 200 à 20000, défaut 6000

non

Caractères de texte à servir dans cet appel.

offset

entier, 0 ou plus, défaut 0

non

Position en caractères où reprendre.

En retour : status, qui vaut ok, instrumental pour un titre sans paroles à chanter, ou no_lyrics pour un titre classé sans elles ; track avec son identifiant, son nom, son artiste, son album, sa durée et son source_url ; plain_lyrics ; synced_lyrics en texte LRC brut et synced_lines en liste de { time_seconds, text }, avec synced_lines_truncated quand la tranche les a coupées. La lecture est décrite par paginated_form, total_chars, returned_chars, offset, next_offset et truncated : redonnez next_offset pour poursuivre, et null marque la fin. attribution est la ligne à citer quand les paroles sont montrées. Un status à instrumental est une réponse complète.

get_track

Lit la fiche d'un titre depuis son identifiant, sans les paroles. Elle confirme une parution avant qu'on demande les paroles, et elle résout un identifiant venu d'un échange précédent.

Argument

Type

Requis

Ce qu'il fait

id

entier, positif

oui

L'identifiant LRCLIB rendu par search_tracks.

En retour : track, qui porte les champs d'une ligne de recherche, et duration_formatted sous la forme m:ss, null pour un titre classé sans durée. has_plain_lyrics et has_synced_lyrics disent quelles formes get_lyrics peut servir.

Configuration

Chaque variable est facultative. Elles se posent dans le bloc env de la configuration du client.

Variable

Défaut

Ce qu'elle fait

LRCLIB_USER_AGENT

l'identité du projet

Nomme votre application auprès de LRCLIB, avec une adresse où joindre une personne.

LRCLIB_MIN_INTERVAL_MS

500

Écart entre deux requêtes, de 200 à 60000. Une valeur sous le plancher est refusée au profit de celle-ci.

LRCLIB_TIMEOUT_MS

15000

Délai d'une requête, de 1000 à 120000.

LRCLIB_MAX_RETRIES

3

Tentatives après un échec passager, de 0 à 10.

LRCLIB_CACHE_TTL_MS

900000

Durée pendant laquelle une réponse reste en mémoire, de 0 à 86400000.

LRCLIB_CACHE_MAX_ENTRIES

200

Réponses gardées en mémoire à la fois, de 0 à 10000.

LRCLIB_LOG_LEVEL

error

silent, error, info ou debug, écrit sur la sortie d'erreur.

Une valeur hors de sa plage retombe sur le défaut, et la raison est écrite sur la sortie d'erreur.

Erreurs

Chaque échec porte un des six codes, un message, et quand cela aide une indication du geste suivant.

Code

Ce qui s'est passé

Que faire

not_found

LRCLIB a répondu, et ne contient pas ce titre.

Vérifiez l'orthographe avec search_tracks.

invalid_input

Les arguments ont été refusés avant toute requête.

Lisez le message, qui nomme l'argument.

rate_limited

LRCLIB demande à ce client de ralentir.

Attendez les secondes indiquées et rappelez avec les mêmes arguments. Le titre est toujours là.

upstream_error

LRCLIB a répondu dans une forme que ce client ne lit pas.

Signalez-le sur le suivi d'incidents.

network_error

La requête n'a pas abouti.

Réessayez sous peu.

timeout

La requête a dépassé son délai.

Augmentez LRCLIB_TIMEOUT_MS, ou demandez un max_chars plus petit.

Comme bibliothèque

La couche qui lit LRCLIB est publiée seule, avec son rythme, son cache et ses erreurs, sans protocole attaché.

import { LrclibClient } from "mcp-lrclib/client";

const client = new LrclibClient();
const { data, cached } = await client.getById(3396226);
console.log(data.track_name, data.synced_lyrics !== null, cached);

search, get et getById répondent chacun { data, cached }, et lèvent une erreur portant un des six codes. Le plancher entre deux requêtes tient également ici.

Rythme et attribution

Les requêtes partent une à une avec un écart minimal entre elles, et ce plancher tient quelle que soit la configuration. Le User-Agent se termine toujours par l'identité du projet et une adresse où joindre une personne. LRCLIB est un service gratuit et publie son API pour être lue par des machines, et ce serveur la lit à la demande, un appel à la fois, en réponse à ce que vous avez demandé.

Chaque résultat porte l'artiste, le titre et l'adresse de sa page LRCLIB, et get_lyrics porte attribution, ces trois éléments écrits en une ligne.

Les paroles sont l'œuvre de leurs auteurs et de leurs éditeurs. Ce projet ne revendique aucun droit dessus, n'embarque aucune base de paroles, n'écrit rien sur le disque et ne contribue rien à LRCLIB. Ce MCP est un projet non officiel, sans affiliation à LRCLIB.

Confidentialité

Ce serveur ne collecte rien sur vous et n'envoie rien à son auteur. Il tourne sur votre machine, ne joint que lrclib.net, garde ses réponses en mémoire le temps qu'il tourne, et n'écrit rien sur le disque. PRIVACY.md dit ce qu'une requête emporte et quels réglages changent cela.

Développement

npm install
npm run build:fixtures
npm test
npm run check

Les tests s'exécutent sur des fixtures engendrées et n'émettent aucune requête. La suite en direct, npm run test:live, émet une requête par route et tourne chaque nuit contre le service lui-même.

Contribuer

Les anomalies, les questions et les idées ont leur place dans le suivi d'incidents. Les propositions de modification sont bienvenues ; ouvrir un ticket d'abord aide à s'accorder sur la forme du changement. Voir CONTRIBUTING.md.

Licence

MIT, voir LICENSE. Les paroles appartiennent à leurs auteurs et à leurs éditeurs, et la base à LRCLIB et à ses contributeurs.

Available Tools

3 tools
get_lyricsGet lyricsA
Read-onlyIdempotent

Fetch the lyrics of one track from LRCLIB, given the id returned by search_tracks, or an exact artist and title. Set 'format' to "synced" for karaoke-style lyrics with a timestamp on every line, "plain" for the text alone, or "both". Check 'has_synced_lyrics' in the search results first: not every track has timed lyrics. Lyrics can be long, so the text is truncated by default: check 'truncated' and call again with 'offset' set to 'next_offset' to continue reading. Instrumental tracks come back with status "instrumental" and no text, which is a valid answer, so do not retry them. Always cite 'attribution' when showing lyrics to a user.

ParametersJSON Schema
NameRequiredDescriptionDefault
idNoLRCLIB track id, as returned by search_tracks. Preferred over the name fields.
formatNo'plain' returns the text only. 'synced' returns LRC text plus a parsed list of timestamped lines. 'both' returns each of them.plain
offsetNoCharacter offset to resume from, for lyrics longer than max_chars.
max_charsNoMaximum characters of lyrics text to return in this call.
album_nameNoAlbum name, to pick between releases.
track_nameNoSong title, matched exactly by LRCLIB. Required when 'id' is absent.
artist_nameNoArtist name, matched exactly by LRCLIB. Required when 'id' is absent.
duration_secondsNoTrack duration, to pick between versions of differing length.

Output Schema

ParametersJSON Schema
NameRequiredDescription
notesYes
trackYes
offsetYes
sourceYes
statusYes
truncatedYes
attributionYes
next_offsetYes
total_charsYes
plain_lyricsYes
synced_linesYesParsed timestamped lines.
synced_lyricsYesRaw LRC text, one timestamp per line.
paginated_formYesWhich body the character counts and the offset describe. Timed text carries its timestamps, so it is longer than the words alone.
returned_charsYes
synced_lines_truncatedYes

TDQS

A4.8/5.0
Behavior5/5

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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds valuable details beyond annotations: default truncation with 'truncated'/'next_offset', instrumental status as a valid no-retry outcome, and the attribution requirement. 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.

Conciseness5/5

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

Five dense sentences, each carrying distinct operational information. Purpose is front-loaded, and there is no filler or redundant restating of schema content.

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?

Despite a complex 8-parameter surface, the description covers all critical runtime behaviors: input selection, format choice, synced availability checking, truncation/continuation, the instrumental edge case, and attribution. The output schema handles return-value details, so nothing essential is missing.

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

Parameters5/5

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

Schema coverage is 100%, so all parameters are already documented. The description goes further by linking id to search_tracks results, clarifying artist/track exact-match semantics as a fallback, explaining format values in user terms, and describing how offset and max_chars interact with truncation flags.

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 clear verb and resource: 'Fetch the lyrics of one track from LRCLIB.' It distinguishes itself from siblings by referencing the id from search_tracks and exact artist/title fallback, making its scope unmistakable.

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

Usage Guidelines4/5

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

Provides strong operational context: how to identify the track, when to expect synced lyrics via has_synced_lyrics, and how to handle instrumental tracks as valid results. It does not explicitly name get_track as the metadata alternative, but the workflow guidance is clear and actionable.

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

get_trackGet track metadataA
Read-onlyIdempotent

Look up one LRCLIB track by its id and return its metadata without the lyrics: title, artist, album, duration, and whether plain and time-synced lyrics exist. Use this to confirm you have the right release or version before calling get_lyrics, or to check whether timed lyrics exist for a track id you already hold.

ParametersJSON Schema
NameRequiredDescriptionDefault
idYesLRCLIB track id, as returned by search_tracks.

Output Schema

ParametersJSON Schema
NameRequiredDescription
notesYes
trackYes
sourceYes
duration_formattedYesDuration as m:ss, when known.

TDQS

A4.5/5.0
Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description is not required to repeat those. The description adds meaningful behavioral context by specifying the return excludes lyrics and includes existence flags for plain and time-synced lyrics, which is not derivable from the schema or annotations alone.

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

Conciseness5/5

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

Two sentences with no filler. The first sentence states the core action and return payload; the second provides focused usage guidance. Everything present earns its place.

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?

The tool is simple, has a single fully documented parameter, rich annotations, and an output schema. The description adds the missing context around when to use the tool and what it returns, making the complete call scenario clear. Nothing necessary for correct invocation is omitted.

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%: the id parameter is already described as 'LRCLIB track id, as returned by search_tracks.' The description does not need to add further parameter detail, so the baseline of 3 applies.

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?

The description uses a specific verb 'Look up' with a clear resource ('one LRCLIB track by its id') and lists the returned fields, distinguishing this from get_lyrics by explicitly stating 'without the lyrics'. This makes the tool's function unambiguous and differentiates it from both siblings.

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?

The description explicitly states when to use this tool: 'confirm you have the right release or version before calling get_lyrics' and 'check whether timed lyrics exist for a track id you already hold.' It references the closest sibling (get_lyrics) as the next step, providing clear routing guidance.

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

search_tracksSearch tracksA
Read-onlyIdempotent

Search LRCLIB for tracks by title, artist or album, and get the id needed to fetch lyrics with get_lyrics. Give either 'query' as free text, or 'track_name' and 'artist_name' separately for a narrower search. Results carry metadata only: title, artist, album, duration, and whether plain and time-synced lyrics exist. Use 'duration_seconds' and 'album_name' in the results to tell releases and re-recordings of the same song apart, and 'has_synced_lyrics' to know whether karaoke-style timed lyrics are available before fetching them. LRCLIB indexes tracks by their metadata, so it cannot search for a word appearing inside the lyrics.

ParametersJSON Schema
NameRequiredDescriptionDefault
limitNoMaximum tracks to return. LRCLIB returns up to 20 per search.
queryNoFree-text search, for example 'nino ferrer le sud'. Use this or the fields below.
album_nameNoAlbum name, to narrow a structured search.
track_nameNoSong title, for a structured search.
artist_nameNoArtist name, for a structured search.

Output Schema

ParametersJSON Schema
NameRequiredDescription
notesYes
sourceYes
resultsYes
result_countYes
total_availableYesTracks LRCLIB returned before applying 'limit'.

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already mark the tool as read-only, idempotent, and non-destructive, and the description adds meaningful behavioral context beyond that: results are metadata-only, tracks are indexed by metadata rather than lyric content, and has_synced_lyrics indicates whether timed lyrics exist before fetching. This is exactly the kind of non-obvious behavior an agent needs to know.

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

Conciseness5/5

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

The description is front-loaded with the core purpose, then parameter guidance, then result interpretation, then a key limitation. Each sentence earns its place and none are filler, making it informative without being bloated.

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 the annotations, output schema, and sibling tools, the description is complete enough to select and invoke the tool correctly. It explains the two search modes, the metadata-only nature of results, how to disambiguate releases, how to check for synced lyrics, and the limitation around lyric-text search. The only minor gap is not addressing get_track directly, but the overall context is still strong.

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 coverage is 100%, so the baseline is 3, but the description adds value by explaining the relationship between parameters: 'query' is free text, while 'track_name' and 'artist_name' provide a narrower structured search. It also explains how result fields like duration_seconds and album_name can be used for disambiguation, going slightly beyond the schema.

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?

The description states a specific verb and resource: 'Search LRCLIB for tracks by title, artist or album', and clarifies that the purpose is to obtain 'the id needed to fetch lyrics with get_lyrics'. This clearly differentiates it from the sibling tools by positioning search as the discovery step before retrieval.

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

Usage Guidelines4/5

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

The description gives solid usage guidance: use 'query' for free text or 'track_name' and 'artist_name' for a narrower search, and it explicitly warns that LRCLIB cannot search lyric content. It names get_lyrics as the downstream consumer, though it does not explicitly contrast search_tracks with get_track or state when get_track would be preferred.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 3 tool updatesv2.0.0
    • Changedget_lyrics19 fields changed
      • addedInput schema / properties / id / maximum
        Added value: +9007199254740991
      • addedInput schema / properties / offset / maximum
        Added value: +9007199254740991
      • changedOutput schema / properties / next_offset / anyOf
        Previous value: -[
        -  {
        -    "type": "integer"
        -  },
        -  {
        -    "type": "null"
        -  }
        -]New value: +[
        +  {
        +    "maximum": 9007199254740991,
        +    "minimum": -9007199254740991,
        +    "type": "integer"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • addedOutput schema / properties / offset / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / offset / minimum
        Added value: +-9007199254740991
      • addedOutput schema / properties / plain_lyrics / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / plain_lyrics / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / returned_chars / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / returned_chars / minimum
        Added value: +-9007199254740991
      • addedOutput schema / properties / synced_lyrics / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / synced_lyrics / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / total_chars / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / total_chars / minimum
        Added value: +-9007199254740991
      • addedOutput schema / properties / track / properties / album_name / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / track / properties / album_name / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / track / properties / duration_seconds / anyOf
        Added value: +[
        +  {
        +    "type": "number"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / track / properties / duration_seconds / type
        Removed value: -[
        -  "number",
        -  "null"
        -]
      • addedOutput schema / properties / track / properties / id / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / track / properties / id / minimum
        Added value: +-9007199254740991
    • Changedget_track9 fields changed
      • addedInput schema / properties / id / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / duration_formatted / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / duration_formatted / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / track / properties / album_name / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / track / properties / album_name / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / track / properties / duration_seconds / anyOf
        Added value: +[
        +  {
        +    "type": "number"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / track / properties / duration_seconds / type
        Removed value: -[
        -  "number",
        -  "null"
        -]
      • addedOutput schema / properties / track / properties / id / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / track / properties / id / minimum
        Added value: +-9007199254740991
    • Changedsearch_tracks10 fields changed
      • addedOutput schema / properties / result_count / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / result_count / minimum
        Added value: +-9007199254740991
      • addedOutput schema / properties / results / items / properties / album_name / anyOf
        Added value: +[
        +  {
        +    "type": "string"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / results / items / properties / album_name / type
        Removed value: -[
        -  "string",
        -  "null"
        -]
      • addedOutput schema / properties / results / items / properties / duration_seconds / anyOf
        Added value: +[
        +  {
        +    "type": "number"
        +  },
        +  {
        +    "type": "null"
        +  }
        +]
      • removedOutput schema / properties / results / items / properties / duration_seconds / type
        Removed value: -[
        -  "number",
        -  "null"
        -]
      • addedOutput schema / properties / results / items / properties / id / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / results / items / properties / id / minimum
        Added value: +-9007199254740991
      • addedOutput schema / properties / total_available / maximum
        Added value: +9007199254740991
      • addedOutput schema / properties / total_available / minimum
        Added value: +-9007199254740991
  2. 1 tool updatev1.4.0
    • Changedget_lyrics2 fields changed
      • addedOutput schema / properties / paginated_form
        Added value: +{
        +  "description": "Which body the character counts and the offset describe. Timed text carries its timestamps, so it is longer than the words alone.",
        +  "enum": [
        +    "plain",
        +    "synced"
        +  ],
        +  "type": "string"
        +}
      • changedOutput schema / required
        Previous value: -[
        -  "status",
        -  "track",
        -  "plain_lyrics",
        -  "synced_lyrics",
        -  "synced_lines",
        -  "synced_lines_truncated",
        -  "total_chars",
        -  "returned_chars",
        -  "offset",
        -  "next_offset",
        -  "truncated",
        -  "attribution",
        -  "source",
        -  "notes"
        -]New value: +[
        +  "status",
        +  "track",
        +  "plain_lyrics",
        +  "synced_lyrics",
        +  "synced_lines",
        +  "synced_lines_truncated",
        +  "paginated_form",
        +  "total_chars",
        +  "returned_chars",
        +  "offset",
        +  "next_offset",
        +  "truncated",
        +  "attribution",
        +  "source",
        +  "notes"
        +]
  3. 3 tool updatesv1.0.0
    • First observedget_lyrics
    • First observedget_track
    • First observedsearch_tracks

TDQS

A4.7/5.0

Scored across 3 tools

Disambiguation4/5

The tools are mostly distinct: search_tracks finds tracks by query while get_track fetches a specific track by ID, and get_lyrics retrieves lyric content. There is minor overlap in that both search_tracks and get_track return metadata, but their purposes are clearly separated by search vs. direct lookup.

Naming Consistency5/5

All tool names follow a consistent verb_noun pattern: search_tracks, get_lyrics, and get_track. The naming is predictable and makes the action and resource type immediately clear.

Tool Count5/5

Three tools is an appropriate scope for an LRCLIB lyrics server. Each tool covers a distinct part of the workflow: searching, fetching lyrics, and fetching track metadata, with no unnecessary duplication.

Completeness5/5

The tool surface covers the full read-only workflow for this domain: discover tracks, inspect metadata, and fetch either plain or synced lyrics. Descriptions also handle edge cases like truncation, instrumental tracks, and timing checks, so there are no obvious dead ends.

Maintenance

ActivityActive
ResponsivenessUnresponsive

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