tabnas MCP server

• Registry namedev.tabnas/mcpverified in the MCP registry

The registry name sits under tabnas.dev. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

• Stateanswerschecked 2026-10-24
• Tools7
• Server calls itselftabnas
• Server version0.1.20
• Protocol version2025-06-18

On 2026-10-24 the server answered initialize and tools/list without a sign-in. First answer in 210 ms.

• Its tools do validate and test declarative grammars before parsing, but not add syntax to an existing grammar through plugins.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

• INITE MCP score78 of 100answers 100 · does the job 50 · definitions 81 · context 100 · use 41 · connects 100
• What an agent can do with it1 of 2 use cases
• Use117 npm downloads a week
• Answered100% of days11 of 11 daily checks
• Median first answer92 ms
• Space in an agent's context≈ 1,412 tokensthe definitions of all its tools (7), which an agent carries on every turn
• Tool definitionsB · 81 of 100
• Typed results0 of 7 toolsdeclared outputSchema: results come typed, read once

• Parameters without a description: in 1 of 7
• Not saying whether it only reads or can destroy: 7 of 7

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

• parse

  Parse input with the tabnas engine. Returns {ok:true, tree} or, on parse failure, {ok:false, diagnostic} — the structured diagnostic described by resource tabnas://schema/diagnostic. An invalid grammar is rejected as {ok:false…

• validate_grammar

  Validate a serialized GrammarSpec. Structural validation against the bundled grammar schema, an engine load in a fresh instance, and a check that every rule reference (`p`, `r`) names a rule the grammar actually defines — a dangling…

• explain_parse_error

  Parse input and explain the failure. Returns {failed:false} when the input parses; otherwise {failed:true, diagnostic, registry} where registry is the error-code registry entry {code,message,hint} for the diagnostic code (resource…

• test_grammar

  Run TSV fixture content against a grammar in a fresh instance, using the fleet fixture convention (@tabnas/support): line 1 is a header, the input column is escape-decoded, the expected column is JSON or ERROR / ERROR:<code>. Returns…

• list_plugins

  List every bundled tabnas plugin descriptor (tabnas.plugin.json of each fleet repo), sorted by name. Returns {plugins:[...]}.

• describe_plugin

  The full descriptor for one plugin, by package name ('@tabnas/csv') or bare fleet name ('csv'). Unknown names get {ok:false, errors} naming the known plugins.

• compare_grammars

  Grammar compatibility (AX plan Phase 5): does candidate grammar B still accept what baseline A accepted, and does it build the same tree for inputs both accept? Returns EVIDENCE AND CONFIDENCE, never a bare verdict: {normalForm, proven[]…