1. A method performed by one or more processing devices, comprising: receiving, from a content provider, a query token that controls distribution of content provided by the content provider; consulting a database stored in memory to determine past performance of the query token when used to distribute content, the past performance comprising performance information indicating how well the query token performed for different match types, where a match type defines what is required to constitute a token match between components of the query token and components of a search query that is submitted by a user; identifying, by the one or more processing devices, a specificity value of the query token that quantifies how specific the query token is based on how rare the query token is in a particular corpus of words; determining, by the one or more processing devices and based on the performance information, differences in performance of the query token between the different match types; determining that the differences in performance meet a threshold difference in performance; in response to the determination that the differences in performance meet the threshold difference in performance, comparing the identified specificity value of the query token that quantifies how specific the query token is to a threshold specificity; selecting, based on the comparing, a match type for the query token, the selecting including: selecting an exact match type for the query token when the specificity of the query token is less than the threshold specificity, wherein selection of the exact match type requires all components of a user submitted query to match the query token for the content to be eligible for distribution; and selecting a phrase match type or broad match type for the query token when the specificity of the query token is greater than the threshold specificity, wherein each of the phrase match type and the broad match type require less of a match than the exact match type; assigning, by the one or more processing devices, the match type to the query token, where assigning comprises storing the match type in association with the query token and content associated with the query token; and comparing the query token to received input of a search query from a user different from the content provider in accordance with the match type to identify the content for output to a display device.