Actually you have the Schema API for that.
The Solr schema API allows using a REST API to get information about the schema.xml
In Solr 4.2 and 4.3, it only allows GET (read-only) access, but in
Solr 4.4, new fields and copyField directives may be added to the schema. Future Solr releases will extend this functionality to allow more schema
elements to be updated
API Entry Points
/collection/schema: retrieve the entire schema
/collection/schema/fields: retrieve information about all defined fields, or create new fields with optional copyField directives
/collection/schema/fields/name: retrieve information about a named field, or create a new named field with optional copyField directives
/collection/schema/dynamicfields: retrieve information about dynamic field rules
/collection/schema/dynamicfields/name: retrieve information about a named dynamic rule
/collection/schema/fieldtypes: retrieve information about field types
/collection/schema/fieldtypes/name: retrieve information about a named field type
/collection/schema/copyfields: retrieve information about copy fields, or create new copyField directives
/collection/schema/name: retrieve the schema name
/collection/schema/version: retrieve the schema version
/collection/schema/uniquekey: retrieve the defined uniqueKey
/collection/schema/similarity: retrieve the global similarity definition
/collection/schema/solrqueryparser/defaultoperator: retrieve the default operator
Examples
Input
Get a list of all fields.
curl http://localhost:8983/solr/collection1/schema/fields?wt=json
Input
Get the entire schema in JSON.
curl http://localhost:8983/solr/collection1/schema?wt=json
More info here: apache-solr-ref-guide-4.5.pdf (search for Schema API)